The cobalt-modified potassium bismuth titanate (K0.5Bi4.5Ti4O15, KBT) piezoelectric ceramics have been prepared using conventional solid state reaction. X-ray diffraction analysis revealed that the cobalt-modified KBT ceramics have a pure four-layer (m = 4) Aurivillius-type structure. The dielectric, ferroelectric, and piezoelectric properties of cobalt-modified KBT ceramics were investigated in detail. The piezoelectric activities of KBT ceramics were significantly improved by the cobalt modification. The reasons for piezoelectric activities enhancement with cobalt modification were given. The piezoelectric coefficient d(33) and Curie temperature T-c for the 5 mol% cobalt-modified KBT ceramics (KBT-Co5) were found to be 28 pC/N and 575 degrees C, respectively. The DC resistivity, frequency constants (N-p and N-t), and electromechanical properties at elevated temperature were investigated, indicating the cobalt-modified KBT piezoelectric ceramics possess stable piezoelectric properties up to 500 degrees C. The results show the cobalt-modified KBT ceramics are potential materials for high temperature piezoelectric applications. (C) 2013 Elsevier B.V. All rights reserved.