diff --git a/neuralNetworkTests.c b/neuralNetworkTests.c
index 21ab370..fb3fb80 100644
--- a/neuralNetworkTests.c
+++ b/neuralNetworkTests.c
@@ -6,9 +6,30 @@
 #include "neuralNetwork.h"
 
 
+static void erzeugeMatrix(FILE *file, const Matrix *m)
+{
+    fwrite(&m->rows, sizeof(int), 1, file);
+    fwrite(&m->cols, sizeof(int), 1, file);
+    fwrite(m->buffer, sizeof(MatrixType), m->rows * m->cols, file);
+}
+
 static void prepareNeuralNetworkFile(const char *path, const NeuralNetwork nn)
 {
-    // TODO
+    FILE *file = fopen(path, "wb");
+    if (!file)
+        return;
+
+    const char *header = "__info2_neural_network_file_format__";
+    fwrite(header, sizeof(char), strlen(header), file);
+    fwrite(&nn.numberOfLayers, sizeof(int), 1, file);
+
+    for (int i = 0; i < nn.numberOfLayers; i++)
+    {
+        erzeugeMatrix(file, &nn.layers[i].weights);
+        erzeugeMatrix(file, &nn.layers[i].biases);
+    }
+
+    fclose(file);
 }
 
 void test_loadModelReturnsCorrectNumberOfLayers(void)