Magnetoelectric (ME) nanocomposites (1 - y) Co0.8Cu0.2Fe2O4 + (y) SrTiO3 (y = 40, 50, 60, 80 and 100%) were prepared by standard ceramic method. Phase formation was checked using X-ray diffraction analysis. Both saturation magnetization (M-s) and Curie temperature (T-C) decrease with increasing SrTiO3 content. Temperature dependence of the dielectric constant reveals two maxima, one about 550 K corresponds to non-stoichiometry and lattice distortions while the second around 900 K corresponds to the Curie temperature (T-C). The large value of ME output is due to the strain induced by lattice distortion in the ferrite phase by Jahn-Teller ions like Cu. Hence, Jahn-Teller effect in the ferrite leads to polarization in the piezoelectric phase. (C) 2013 Elsevier Ltd. All rights reserved.