Crystal structure of the title compound has been determined by X-ray method to the final R factor of 0.058 and compared in detail with similar structures from Cambridge Structural Database. It is composed of flat 4-aminocinnoline-3-carboxylate anions and disodium decahydrate dications domains expanded in [010] direction and joint by a complicated system of hydrogen bonds. A strong intramolecular hydrogen bond between amine and carboxy groups roughly maintains coplanarity of the groups with aromatic cinnoline system.