Department of Chemistry, J. V College (C. C. S. University, Meerut), Baraut (Baghpat), Uttar Pradesh, India E-mail : uchemkhokhar@gmail.com Department of Chemistry, Zakir Husain College (University of Delhi), JLN Marg, New Delhi-110 002, India E-mail: schandra_00@yahoo.com Fax: 91-11-23215906 Manuscript received 26 July 2010, revised 18 November 2010, accepted 13 December 2010 The structures of new cobalt(ll) an copper(ll) complexes derived from 12-membered tetraaza macrocyclic ligand namely dibenzo-[b,g]-5,6,11,12-tetramethyl-1,4, 7,10-tetraazacyclododeca-4, 7-10,12-tetraene have been elucidated after their synthesis by using various physico-chemical methods viz. elemental analysis, molar conductivity measurements, solid state room temperature magnetic susceptibility, spectral (IR, electronic, mass and EPR) and thermal analysis. The IR frequencies were in accordance with d-d absorption frequencies. IR spectra suggested that ligand was coordinated to the metal ion in a tetradentate fashion through azomethine nitrogen atoms. The g values were calculated from EPR spectra for Cull complexes indicated the presence of the unpaired electron in the dx2-y2 orbital. The electronic spectra suggest an octahedral and tetragonal structure around Coll and Cull metal ion respectively. Electrochemical behavior of the complex [CuLCI2] has also been discussed. TG studies suggested the absence of water molecules inside or outside the coordination sphere.