The nitrosyl complex [Cr(dmso)₅(NO)](PF₆)₂ (1) (dmso = dimethyl sulfoxide) has been prepared by the solvolysis of [Cr(NCCH₃)₅(NO)](PF₆)₂ in neat dmso. The compound 1 crystallizes in orthorhombic space group Pna2₁ with a = 11.3370(15), b = 24.0790(5), and c = 11.007(3) Å at 122 K with an almost linear Cr-N-O angle (176.45(13)°). The optical absorption spectrum of 1 in dmso shows maxima at 734, 567, 450, 413, and 337 nm. Continuous photolysis of 1 with l = 365 - 580 nm light in dmso solution results in a release of NO with quantum yield, F, in the range 0.034 - 0.108 mol×Einstein^-1. Irradiation of a deoxygenated CH₃CN solution of [Cr(NCCH₃)₅(NO)](PF₆)₂ in the presence of excess of [Fe(S₂CNEt₂)₂] results in a transfer of NO to the iron centre as shown from the characteristic EPR spectrum of [Fe(S₂CNEt₂)₂(NO)] with A_iso(¹⁴N) = 12.2´10^-4 cm^-1. The EPR parameters of 1 were determined: g_iso, g_¦ and g_-: 1.96725, 1.91881(4) and 1.992763(2); A_iso(⁵³Cr), A_¦(⁵³Cr) and A_-(⁵³Cr): 22.8´10^-4, 39´10^-4 and 15.8´10^-4cm^-1; A_iso(¹⁴N), A_¦(¹⁴N) and A_-(¹⁴N): 5.9´10^-4, 2´10^-4 and 7.540(4)´10^-4 cm^-1. The pseudo-first-order rate constant, k, for the substitution of the dmso ligands in 1 with dmso has been found by ¹H NMR in dmso-d₆ solution in the temperature range 293 - 308 K to be k = (8.95 ± 0.09) ´10^-4 s^-1 (t_½ = 12.9 ± 0.1 min) at 298 K with DH^‡ = 100(2) kJ×mol^-1 and DS^‡ = 32(5) J×mol^-1×K^-1.