P.G. Department of Chemistry, Sambalpur University, Jyoti Vihar, Burla, Sambalpur-768 019, Orissa, India E-mail : dhruba_dash@yahoo.co.in Manuscript received 16 April 2008, revised 1 July 2008, accepted 1 August 2008 A series of complexes of the type [M(L)(NO3)2].mH2O and [VO(L)(SO4)].2H2O, where L is a Schiff base 1,10-dihydroxy-2,3,8,9-tetramethyl-1,4, 7, 10-tetraza-dec-1,3, 7 ,9-tetraene (DHTTDT) or 5:6-benzo-1, 10-dihydroxy-2,3,8,9- tetramethyl-1,4, 7, 10-tetraza-dec-1 ,3, 7 ,9-tetraene (BDHTTDT) derived from ethylenediamine/o-phenylene diamine and diacetyl monoxime have been synthesized (M = ZrOIV, UO2VI and ThIV; m = 1, 2 and 3 respectively). All the complexes are characterized on the basis of elemental analysis, thermal analysis, molar conductivity, magnetic moment, electronic, infrared, 1H NMR and ESR spectral studies. The results indicate that the VOIV ion is penta co-ordinated yielding paramagnetic complexes where as UO2VI, ZrOIV ions are hexa co-ordinated and ThIV ion is octa co-ordinated yielding diamagnetic complexes of above composition.