Cu(II) complexes of eight N,N,O-donor hydrazone ligands, obtained by condensation of pyridine-2-carbaldehyde and 2-acetylpyridine with four aroyl hydrazides, are reported. Reactions of Cu(ClO4)2· 6H2O with the pyridine-2-carbaldehyde hydrazones (L1H, L2H, L3H, L4H) in presence of Et3N, in 1:2:2 molar ratio, lead to isolation of mononuclear octahedral Cu(II) complexes of formula [Cu(L)2] (L = L1 -, L 2 -, L3 -, L4 -). However, for the 2-acetylpyridine hydrazones (L5H, L6H, L7H, L8H) reactions under similar conditions yield dichloro bridged complexes of the type [Cu2(μ-Cl) 2(L′)2] (L′ = L5 -, L6 -, L7 -, L8 -), where each Cu(II) ion is in a square-pyramidal geometry, the chloride ions coming from the in situ reduction of perchlorate by the 2-acetylpyridine hydrazones. The X-ray crystal structures of [Cu(L 1)2] and [Cu2(μ-Cl)2(L 5)2] are reported. The spectroscopic and electrochemical behaviors of the complexes are also reported.© 2012 Elsevier B.V. All rights reserved.