Copper (II) complexes of chromen-2-one-3-carboxyhydrazide and 2-(chromen-3'-onyl)-5- (aryl)-1, 3, 4-oxadiazole derivatives have been synthesized. The structural features have been determined from their microanalytical, magnetic susceptibility, molar conductance, IR, UV Vis, 1H NMR and ESR spectral data. All the Cu (II) complexes exhibit the composition Cu (Ln) 2X2; where L1= chromen-2-one-3-carboxy hydrazide, L2= 2-(chromen-3'-onyl)-5-(2ʺ ...