Two new copper(II) and nickel(II) complexes [Cu(MeOH)(O-NO2)(L)](NO3)center dot CH3OH (1) and [Ni(L)(2)(NO3)(2)]center dot H2O (2) derived from the 4'-(2-thienyl)-2,2',6',2 ''-terpyridine (L) were synthesized. The ligand and complexes were characterized with elemental analysis, H-1 and C-13 NMR, IR spectroscopy and finally the solid structure of complexes were determined by X-ray crystallography. Complexes (1) and (2) were tested as homogenous catalysts for sulfoxidation of a variety of organosulfide substrates utilizing hydrogen peroxide in the presence of a catalytic amount of trimethylamine N-oxide (TMAO). Addition of TMAO to the reaction mixture enhanced the conversion and selectivity. (C) 2010 Elsevier B.V. All rights reserved.