diff --git a/src/Platform/GridSearch.cc b/src/Platform/GridSearch.cc
index e6b25af..20fed05 100644
--- a/src/Platform/GridSearch.cc
+++ b/src/Platform/GridSearch.cc
@@ -63,7 +63,7 @@ namespace platform {
                 return Colors::RESET();
         }
     }
-    double GridSearch::processFile(std::string fileName, Datasets& datasets, HyperParameters& hyperparameters)
+    double GridSearch::processFileSingle(std::string fileName, Datasets& datasets, HyperParameters& hyperparameters)
     {
         // Get dataset
         auto [X, y] = datasets.getTensors(fileName);
@@ -135,11 +135,8 @@ namespace platform {
         }
         return datasets_names;
     }
-
-    void GridSearch::go()
+    json GridSearch::initializeResults()
     {
-        auto datasets = Datasets(config.discretize, Paths::datasets());
-        auto datasets_names = processDatasets(datasets);
         // Load previous results
         json results;
         if (config.continue_from != "No") {
@@ -149,6 +146,7 @@ namespace platform {
                 std::ifstream file(Paths::grid_output(config.model));
                 if (file.is_open()) {
                     results = json::parse(file);
+                    results = results["results"];
                 }
             }
             catch (const std::exception& e) {
@@ -157,7 +155,15 @@ namespace platform {
                 results = json();
             }
         }
-        std::cout << "***************** Starting Gridsearch *****************" << std::endl;
+        return results;
+    }
+
+    void GridSearch::goSingle()
+    {
+        auto datasets = Datasets(config.discretize, Paths::datasets());
+        auto datasets_names = processDatasets(datasets);
+        json results = initializeResults();
+        std::cout << "***************** Starting Single Gridsearch *****************" << std::endl;
         std::cout << "input file=" << Paths::grid_input(config.model) << std::endl;
         auto grid = GridData(Paths::grid_input(config.model));
         // Generate hyperparameters grid & run gridsearch
@@ -174,7 +180,7 @@ namespace platform {
                 if (!config.quiet)
                     showProgressComb(++num, totalComb, Colors::CYAN());
                 auto hyperparameters = platform::HyperParameters(datasets.getNames(), hyperparam_line);
-                double score = processFile(dataset, datasets, hyperparameters);
+                double score = processFileSingle(dataset, datasets, hyperparameters);
                 if (score > bestScore) {
                     bestScore = score;
                     bestHyperparameters = hyperparam_line;
@@ -184,20 +190,80 @@ namespace platform {
                 std::cout << "end." << " Score: " << setw(9) << setprecision(7) << fixed
                     << bestScore << " [" << bestHyperparameters.dump() << "]" << std::endl;
             }
-            results[dataset]["score"] = bestScore;
-            results[dataset]["hyperparameters"] = bestHyperparameters;
-            results[dataset]["date"] = get_date() + " " + get_time();
-            results[dataset]["grid"] = grid.getInputGrid(dataset);
+            json result = {
+                { "score", bestScore },
+                { "hyperparameters", bestHyperparameters },
+                { "date", get_date() + " " + get_time() },
+                { "grid", grid.getInputGrid(dataset) }
+            };
+            results[dataset] = result;
             // Save partial results
             save(results);
         }
         // Save final results
         save(results);
-        std::cout << "***************** Ending Gridsearch *******************" << std::endl;
+        std::cout << "***************** Ending Single Gridsearch *******************" << std::endl;
+    }
+    void GridSearch::goNested()
+    {
+        auto datasets = Datasets(config.discretize, Paths::datasets());
+        auto datasets_names = processDatasets(datasets);
+        json results = initializeResults();
+        std::cout << "***************** Starting Nested Gridsearch *****************" << std::endl;
+        std::cout << "input file=" << Paths::grid_input(config.model) << std::endl;
+        auto grid = GridData(Paths::grid_input(config.model));
+        // Generate hyperparameters grid & run gridsearch
+        // Check each combination of hyperparameters for each dataset and each seed
+        for (const auto& dataset : datasets_names) {
+            auto totalComb = grid.getNumCombinations(dataset);
+            if (!config.quiet)
+                std::cout << "- " << setw(20) << left << dataset << " " << right << flush;
+            int num = 0;
+            double bestScore = 0.0;
+            json bestHyperparameters;
+            auto combinations = grid.getGrid(dataset);
+            for (const auto& hyperparam_line : combinations) {
+                if (!config.quiet)
+                    showProgressComb(++num, totalComb, Colors::CYAN());
+                auto hyperparameters = platform::HyperParameters(datasets.getNames(), hyperparam_line);
+                double score = processFileSingle(dataset, datasets, hyperparameters);
+                if (score > bestScore) {
+                    bestScore = score;
+                    bestHyperparameters = hyperparam_line;
+                }
+            }
+            if (!config.quiet) {
+                std::cout << "end." << " Score: " << setw(9) << setprecision(7) << fixed
+                    << bestScore << " [" << bestHyperparameters.dump() << "]" << std::endl;
+            }
+            json result = {
+                { "score", bestScore },
+                { "hyperparameters", bestHyperparameters },
+                { "date", get_date() + " " + get_time() },
+                { "grid", grid.getInputGrid(dataset) }
+            };
+            results[dataset] = result;
+            // Save partial results
+            save(results);
+        }
+        // Save final results
+        save(results);
+        std::cout << "***************** Ending Nested Gridsearch *******************" << std::endl;
     }
     void GridSearch::save(json& results) const
     {
         std::ofstream file(Paths::grid_output(config.model));
-        file << results.dump(4);
+        json output = {
+            { "model", config.model },
+            { "score", config.score },
+            { "discretize", config.discretize },
+            { "stratified", config.stratified },
+            { "n_folds", config.n_folds },
+            { "seeds", config.seeds },
+            { "date", get_date() + " " + get_time()},
+            { "nested", config.nested},
+            { "results", results }
+        };
+        file << output.dump(4);
     }
 } /* namespace platform */
\ No newline at end of file
diff --git a/src/Platform/GridSearch.h b/src/Platform/GridSearch.h
index e8bfb85..d27c59d 100644
--- a/src/Platform/GridSearch.h
+++ b/src/Platform/GridSearch.h
@@ -17,19 +17,22 @@ namespace platform {
         bool only; // used with continue_from to only compute that dataset
         bool discretize;
         bool stratified;
+        int nested;
         int n_folds;
         std::vector<int> seeds;
     };
     class GridSearch {
     public:
         explicit GridSearch(struct ConfigGrid& config);
-        void go();
+        void goSingle();
+        void goNested();
         ~GridSearch() = default;
         json getResults();
     private:
         void save(json& results) const;
+        json initializeResults();
         vector<std::string> processDatasets(Datasets& datasets);
-        double processFile(std::string fileName, Datasets& datasets, HyperParameters& hyperparameters);
+        double processFileSingle(std::string fileName, Datasets& datasets, HyperParameters& hyperparameters);
         struct ConfigGrid config;
     };
 } /* namespace platform */
diff --git a/src/Platform/b_grid.cc b/src/Platform/b_grid.cc
index 64452ed..f190c5d 100644
--- a/src/Platform/b_grid.cc
+++ b/src/Platform/b_grid.cc
@@ -11,6 +11,7 @@
 #include "Colors.h"
 
 using json = nlohmann::json;
+const int MAXL = 133;
 
 void manageArguments(argparse::ArgumentParser& program)
 {
@@ -27,13 +28,14 @@ void manageArguments(argparse::ArgumentParser& program)
             }
     );
     group.add_argument("--dump").help("Show the grid combinations").default_value(false).implicit_value(true);
-    group.add_argument("--list").help("List the computed hyperparameters").default_value(false).implicit_value(true);
+    group.add_argument("--report").help("Report the computed hyperparameters").default_value(false).implicit_value(true);
     group.add_argument("--compute").help("Perform computation of the grid output hyperparameters").default_value(false).implicit_value(true);
     program.add_argument("--discretize").help("Discretize input datasets").default_value((bool)stoi(env.get("discretize"))).implicit_value(true);
     program.add_argument("--stratified").help("If Stratified KFold is to be done").default_value((bool)stoi(env.get("stratified"))).implicit_value(true);
     program.add_argument("--quiet").help("Don't display detailed progress").default_value(false).implicit_value(true);
     program.add_argument("--continue").help("Continue computing from that dataset").default_value("No");
     program.add_argument("--only").help("Used with continue to compute that dataset only").default_value(false).implicit_value(true);
+    program.add_argument("--nested").help("Do a double/nested cross validation with n folds").default_value(0).scan<'i', int>();
     program.add_argument("--score").help("Score used in gridsearch").default_value("accuracy");
     program.add_argument("-f", "--folds").help("Number of folds").default_value(stoi(env.get("n_folds"))).scan<'i', int>().action([](const std::string& value) {
         try {
@@ -83,13 +85,29 @@ void list_dump(std::string& model)
     }
     std::cout << Colors::RESET() << std::endl;
 }
+std::string headerLine(const std::string& text, int utf = 0)
+{
+    int n = MAXL - text.length() - 3;
+    n = n < 0 ? 0 : n;
+    return "* " + text + std::string(n + utf, ' ') + "*\n";
+}
 void list_results(json& results, std::string& model)
 {
-    std::cout << Colors::MAGENTA() << "Listing computed hyperparameters for model "
-        << model << std::endl << std::endl;
+    std::cout << Colors::MAGENTA() << std::string(MAXL, '*') << std::endl;
+    std::cout << headerLine("Listing computed hyperparameters for model " + model);
+    std::cout << headerLine("Date & time: " + results["date"].get<std::string>());
+    std::cout << headerLine("Score: " + results["score"].get<std::string>());
+    std::cout << headerLine(
+        "Random seeds: " + results["seeds"].dump()
+        + " Discretized: " + (results["discretize"].get<bool>() ? "True" : "False")
+        + " Stratified: " + (results["stratified"].get<bool>() ? "True" : "False")
+        + " #Folds: " + std::to_string(results["n_folds"].get<int>())
+        + " Nested: " + (results["nested"].get<int>() == 0 ? "False" : to_string(results["nested"].get<int>()))
+    );
+    std::cout << std::string(MAXL, '*') << std::endl;
     int spaces = 0;
     int hyperparameters_spaces = 0;
-    for (const auto& item : results.items()) {
+    for (const auto& item : results["results"].items()) {
         auto key = item.key();
         auto value = item.value();
         if (key.size() > spaces) {
@@ -105,7 +123,7 @@ void list_results(json& results, std::string& model)
         << string(hyperparameters_spaces, '=') << std::endl;
     bool odd = true;
     int index = 0;
-    for (const auto& item : results.items()) {
+    for (const auto& item : results["results"].items()) {
         auto color = odd ? Colors::CYAN() : Colors::BLUE();
         auto key = item.key();
         auto value = item.value();
@@ -119,12 +137,16 @@ void list_results(json& results, std::string& model)
     std::cout << Colors::RESET() << std::endl;
 }
 
+
+/*
+ * Main
+ */
 int main(int argc, char** argv)
 {
     argparse::ArgumentParser program("b_grid");
     manageArguments(program);
     struct platform::ConfigGrid config;
-    bool dump, compute, list;
+    bool dump, compute;
     try {
         program.parse_args(argc, argv);
         config.model = program.get<std::string>("model");
@@ -135,13 +157,13 @@ int main(int argc, char** argv)
         config.quiet = program.get<bool>("quiet");
         config.only = program.get<bool>("only");
         config.seeds = program.get<std::vector<int>>("seeds");
+        config.nested = program.get<int>("nested");
         config.continue_from = program.get<std::string>("continue");
         if (config.continue_from == "No" && config.only) {
             throw std::runtime_error("Cannot use --only without --continue");
         }
         dump = program.get<bool>("dump");
         compute = program.get<bool>("compute");
-        list = program.get<bool>("list");
         if (dump && (config.continue_from != "No" || config.only)) {
             throw std::runtime_error("Cannot use --dump with --continue or --only");
         }
@@ -163,7 +185,10 @@ int main(int argc, char** argv)
         list_dump(config.model);
     } else {
         if (compute) {
-            grid_search.go();
+            if (config.nested == 0)
+                grid_search.goSingle();
+            else
+                grid_search.goNested();
             std::cout << "Process took " << timer.getDurationString() << std::endl;
         } else {
             // List results