Two novel Cu(II) complexes with the ligand pyridine-2-carboxaldehyde 4-hydroxy benzoyl hydrazone ligand (HL) have been successfully prepared and their crystalline structures are reported. These pseudohalide-bridged copper(II) complexes [{Cu(L)(mu(1,1)-N3)}(2)] (1) and {Cu(L)(NCS)(MeOH)} (2) were characterised by elemental analysis, IR and UV-Vis spectroscopy. Their solid-state structures were determined by single-crystal X-ray diffraction analysis which revealed that 1 is a mu(1,1)-N-3-bridged dimer, whereas 2 is a mononuclear based structure. Supramolecular interactions involving the adjacent complexes were investigated in detail. The efficiency of the ligand and the two complexes was evaluated against the bacteria Entrobacter facealis, Staphytococcus aureus, Entrobacter aerogenes, Escherichia coli, Klebsiella pneumonia and Proteus mirabilis, with the complexes demonstrating enhanced activity relatively to the free ligand.