A novel series of Cu(II) complexes of azo rhodanine derivatives [CuLn(OAc)(OH2)]2H(2)O (n = 1, R = OCH3; n = 2, CH3; n = 3, H; and n = 4, NO2) have been synthesized. The alternating current conductivity (sigma(ac)) dielectric properties of Cu(II) complexes of azo rhodanine derivatives were investigated in the frequency range 0.1-100 kHz and temperature range 303-600K. The values of the thermal activation energies of electrical conductivity Delta E-1 and Delta E-2 for all Cu(II) complexes [CuLn(OAc)(OH2)]2H(2)O were calculated at different frequencies. The conductivity depends on the substituents of the complexes. The correlated barrier hopping (CBH) is the dominant conduction mechanism for complexes [CuLn(OAc)(OH2)]2H(2)O (n=1, 2 and 4) while for complex [CuL3(OAc)(OH2)]2H(2)O the small polarons tunneling (SPT) is the dominant conduction mechanism. (C) 2015 Elsevier Ltd. All rights reserved.