A series of novel octahedral nickel(II) dithiocarbamate complexes involving bidentate nitrogen-donor ligands (phen=1,10-phenanthroline, bpy=2,2′-bipyridine) or a tetradentate ligand (cyclam=1,4,8,11-tetraazacycloteradecane) of the composition [Ni(BzMetdtc)(phen) 2 ]ClO 4 (1), [Ni(Pe 2 dtc)(phen) 2 ]ClO 4 (2), [Ni(Bzppzdtc)(phen) 2 ]ClO 4 ·CHCl 3 (3), [Ni(Bzppzdtc)(phen) 2 ](SCN) (4), [Ni(BzMetdtc)(bpy) 2 ]ClO 4 ·2H 2 O (5), [Ni(Pe 2 dtc)(cyclam)]ClO 4 (6), [Ni(BzMetdtc) 2 (cyclam)] (7), [Ni(Bz 2 dtc) 2 (cyclam)] (8) and [Ni(Bz 2 dtc) 2 (phen)] (9) (BzMetdtc=N,N-benzyl-methyldithiocarbamate(1-) anion, Pe 2 dtc=N,N-dipentyldithiocarbamate(1-) anion, Bz 2 dtc=N,N-dibenzyldithiocarbamate(1-) anion, Bzppzdtc=4-benzylpiperazinedithiocarbamate(1-) anion), have been synthesized. Spectroscopic (electronic and infrared), magnetic moment and molar conductivity data, and thermal behaviour of the complexes are discussed. Single crystal X-ray analysis of 3 and 8 confirmed a distorted octahedral arrangement in the vicinity of the nickel atom with a N 4 S 2 donor set. They represent the first X-ray structures of such type complexes. The catalytic influence of complexes 2, 3, 6, and 7 on graphite oxidation was studied and discussed.