The Aurivillius type potassium lanthanum bismuth titanate (K0.5La0.5Bi4Ti4O15, KLBT) polycrystalline ceramics with 0.0-1.0 wt.% CeO2 were synthesized using conventional solid-state processing. X-ray diffraction analysis revealed that the cerium-modified KLBT ceramics have a pure four-layer Aurivillius type structure. The effects of cerium oxide on the piezoelectric, ferroelectric and dielectric properties on the KLBT ceramics were investigated. By the cerium modification, the piezoelectric activities of KLBT ceramics were significantly improved and the dielectric loss decreased. The piezoelectric coefficient d(33) for the 0.50 wt.% CeO2-modified KLBT was found to be 28 pC N-1, the highest value among the modified KLBT-based piezoceramics. The reason for piezoelectric activities enhancement with Ce modification was given. The dielectric spectroscopy presented that the Curie temperature for all the KLBT ceramics is higher than 400 degrees C. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.