The synthesis and crystal structure of the title compound, K+. C5H9N2O
2S2-. 2H(2)O, are described. The structure consists of potassium catio
ns, 3-dithiocarboxy-3-aza-5-aminopentanoate anions and molecules of wa
ter. The anion exists in two tautomeric forms, each described by two r
esonance structures.