The title compound, C15H12N6O9Pt, consists of [Pt(terpy)ONO2](+) cation and [H(ONO2)(2)](-) anion, in which 2 nitrate groups are linked by a strong hydrogen bond [(OO)-O-... 2449(1) angstrom]. In the cation, the terpyridine is coordinated to Pt as a tridentate ligand and the fourth position is occupied by the nitrate ion's oxygen. The coordination around Pt is square-planar. The coordinated nitrate moiety adopts a distorted trigonal-planar configuration. It belongs to the space group P (1) over bar with a = 8.605(2), b = 10.220(3) angstrom, c = 10.517(2) angstrom and alpha = 89.51(1), beta = 82.78(2), gamma = 76.90(2)degrees.