The positive temperature coefficient resistance (PTCR) effect of BaTiO3-based ceramics is strongly influenced by the doping of donor and acceptor. Some 3d acceptors such as Mn, Fe, Cu can enhance it greatly, whereas this is not the case for the other acceptors such as K, Na, Ni, Mg. The effect can also be enhanced by the doping of Bi2O3 vapor during sintering in BaTiO3-based ceramics; in this case, the enhancement of PTCR effect of the sample codoped with manganese is much greater than that only doped with donor. This is because that excess donor can be compensated by codoped manganese and form more stable composite trap centers, and the PTCR effects can be enhanced more distinctly. (C) 2002 Elsevier Science B.V. All tights reserved.