A reaction of nitric acid with [RuNO(Py)2(NO2)2OH] without heating is shown to result in the complete substitution of nitro and hydroxo ligands with the formation of [RuNO(Py)2(NO3)3] (1). The high lability of nitrate ligands allows their subsequent substitution with the formation of [RuNO(Py)3(NO3)(OH)](NO3) complex (2). The compounds are characterized by the elemental analysis and IR spectroscopy. Their crystal structures are determined by X-ray crystallography. The crystallographic data for complex 1 are: a = 8.9174(4) Å, b = 12.2822(5) Å, c = 15.9104(6) Å, β = 94.4160(10)°, space group P21/c, Z = 4, R = 0.0468 [I > 2σ(I)]; for complex 2: a = 10.8147(4) Å, b = 12.6004(5) Å, c = 14.2201(5) Å, β = 101.5750(10)°, space group Cc, Z = 4, R = 0.0174. Complex 1 is obtained as a facial isomer. Oxygen atoms of coordinated nitrate ligands occupy one of the faces of a distorted RuN3O3 octahedron. In complex 2, the hydroxo ligand is coordinated in the trans-position to the nitroso group. The equatorial positions in the octahedral ruthenium environment are occupied by three nitrogen atoms of pyridine ligands and the oxygen atom of the nitrate ligand.