Heat-electric properties at high temperatures were measured on tungsten trioxide (WO3) ceramics doped with Tb4O7 prepared by c onventional solid-sintering method. The results indicated that a phase transition occurred at 350℃ on heating and 270℃ on cooling with a large thermal hysteresis of about 80℃. And the samples can provide an electric energy output at a constant temperature of 500℃, which cannot be explained by the known thermoelectric or pyroelectric effect. We regard it as a new heat-electric effect, by which a new way of converting heat energy to electric energy may be found.