Ultrafine and homogeneous positive temperature coefficient of resistivity (PTCR) powder was prepared by two chemical steps : citrate and liquid-phase coating process. The physical and chemical properties of the powder were investigated in detail. The dimensions of the primary particles in the PTCR powders were about 20-50 nm. Sintering aids and acceptors could be distributed homogeneously in doped BaTiO3 powder through the liquid-phase coating process. Sintered from this powder produced samples with excellent PTCR effects (Delta R = 10(6), Delta T = 110 degrees, alpha(30) = 26% degrees C-1).