Icy bodies in space are being irradiated continuously by ionizing radiation. Therefore, the transformation of organic molecules trapped in extraterrestrial ices might have been possible. This work studied a bulk irradiation of a mixture of some constituents of cometary nuclei. The results show that the formation of different compounds, among them ammonia, carbon dioxide, amines, ureas, free amino acids, and oligomeric material, yields carboxylic acids, amino acids, and purines upon hydrolysis.