Reaction of cis-Ru(bisox)₂Cl₂, where bisox is 4,4,4′,4′-tetramethyl-2,2′-bisoxazoline, with HNO₃ in 1 : 4 molar proportion in boiling water under N₂ atmosphere and subsequent addition of an excess of NaClO₄·H₂O yields [Ru(bisox)(HL)(NO)](ClO₄)(NO₃) (1). HL is a hydrolysed form of bisox where one of the oxazoline rings opens up. X-Ray crystallography shows that 1 contains an octahedral RuN₅O core. HL binds the metal through an imino N, an amide N and an alcoholic O atom. Reaction of cis-Ru(bisox)₂Cl₂ with an excess of NaNO₂ in water gives cis-Ru(bisox)₂(NO₂)₂ (2). On acidification by HClO₄ in methanol, 2 is smoothly converted to cis-[Ru(bisox)₂(NO₂)(NO)](ClO₄)₂ (3) due to equilibrium (1).NO₂⁻ + H⁺ ⇌ NO⁺ + OH⁻The X-ray crystal structures of 2 and 3 have also been determined. NO binds Ru in 1 and 3 linearly. The Ru–NO bond length in 1 is 1.764(13) Å and that in 3 is ∼1.78 Å. All the three complexes have been characterised by FTIR, NMR and ESIMS. The NO stretching frequencies in 1 and 3 are 1897 and 1936 cm⁻¹ respectively. While 3 reverts back to 2 readily in presence of OH⁻ [equilibrium (1)], 1 does not react with OH⁻. It is concluded that while in the reaction of cis-Ru(bisox)₂Cl₂ with HNO₃, bisox is hydrolysed following abstraction of NO from HNO₃, generation of the nitrosyl complex 3viareaction (1) is not accompanied with such hydrolysis.