In the title compound, [PtCl2(C13H21N5)]·0.5CH3NO2, the Pt(II) atom is coordinated in a slightly distorted square-planar geometry by two Cl atoms and two N atoms of the bidentate ligand. The (1,3,5-tri-aza-penta-diene)Pt(II) metalla ring is slightly bent and does not conjugate with the aromatic ring. In the crystal, N-H⋯Cl hydrogen bonds link the complex mol-ecules, forming chains along [001]. The nitromethane solvent molecule shows half-occupancy and is disordered over two sets of sites about an inversion centre.