The solid solutions of (1-x)PbSc0.5Ta0.5O3-(x)PbHfO3 (PSTH(x)) with pure perovskite structure were fabricated by hot-pressing sintering method. The structural, dielectric, and pyroelectric properties of the PSTH(x) ceramics were investigated. It was found that the long-range ordering decreased and the grain size increased with the increase of x. The maximum dielectric constant of 21 000 at 100 Hz and the highest pyroelectric coefficient of 615 x 10-8 C center dot(cm2 center dot K)-1 were obtained for an x value of 0.15, where the PSTH(x) ceramic showed the largest lattice distortion.