A new Cr III complex, viz. trans-[Cr(naphprn)(H 2 O) 2 ]ClO 4 AE 2H 2 O, (1) {naphprn ¼ N,N¢-trimethylenebis(naphthylideneimine)} has been synthesized and characterized. Aquo ligand substitution of (1) by the azide ligand gave rise to trans-[Cr(naphprn)(N 3 )(H 2 O)], (2). Irradiation of (2) in DMF gave nitrido(naphprn)chromium(V) (3). Solutions of (3) showed e.p.r. spectra at room temperature (g iso ¼ 1.9865). The i.r. spectra showed disappearance of a band at 2067 cm )1 showing the breakdown of NBN and appearance of a new band at 1074 cm )1 which is assigned to the CrB 14 N, stretching frequency indicating the formation of a nitrido chromium(V) complex, (3). The u.v.-vis. spectrum of complex (3) exhibited a d-d band maximum at 553 nm (e ¼ 120 M )1 cm )1 ). The rate of formation of (2) was found to be 5.0 · 10 )3 M )1 s )1 in an aqueous acidic medium at [Cr III ] ¼ 0.5 · 10 )3 M; [N 3 ) ] ¼ 0.01-0.15 M; [H + ] ¼ 0.001 M and I ¼ 0.2 M (LiClO 4 ). The rate of photo-decomposition of (2) to give rise to (3) was found to be 0.15 · 10 )3 s )1 in DMF.