Tetra-ethyl-ammonium l-malate 1.36-hydrate.

The asymmetric unit of the title compound, C(8)H(20)N(+)·C(4)H(5)O(5) (-)·1.36H(2)O, contains two independent ion pairs, with similar conformations, and three water mol-ecules of crystallization, one water mol-ecule haing a site-occupancy factor of 0.721 (5). Intra-molecular O-H⋯O hydrogen bonds, involving the hydr-oxy groups and an O atom of each carboxyl-ate anion, generate five-membered rings involving S(5) ring motifs. In the crystal structure, mol-ecules are linked together by water mol-ecules through four-membered O-H⋯O-H⋯O-H inter-actions to form one-dimensional infinite chains along the a axis. Since the mol-ecules are also linked into one-dimensional infinite chains along the b axis, mol-ecular sheets parallel to the (001) plane are created. Overall, the crystal structure is stabilized by two intra-molecular O-H⋯O hydrogen bonds, nine inter-molecular O-H⋯O and ten C-H⋯O hydrogen bonds.