Complexes of 2,6 dimethyl 3,5 pyridinedicarboxylic acid dihydrazide (DH) with copper(II) and cobalt(II) nitrates and sulfates have been studied by IR and UV spectroscopy, DTA, and X ray crystallogra phy. The complexation results in polynuclear compounds of the {[M(DH)(ROH) n ]An m } z composition (M = Cu 2+ , Co 2+ ; An = ; R = H, i Pr; n = 0.5-4, m = 1.2, z ≥ 4) containing bidentate DH bridges coordinated to the metal through the carbonyl oxygen atom and the amino group nitrogen atom of the hydrazide moiety.