In the title compound, (C6H9N2)[Cr(C2O4)2(H2O)2]·H2O, the Cr(III) atom adopts a slightly distorted octa-hedral coordination environment defined by two chelating oxalate ligands in the equatorial plane and two water mol-ecules in axial positions. A three-dimensional network is generated by inter-molecular N-H⋯O and O-H⋯O hydrogen-bonding interactions involving the cation, the complex anion and the lattice water molecule.