Silver doped 0.61PbMg(0.28)Nb(0.67)Zr(0.52)O(3)-0.39PbTiO(3) relaxor ferroelectrics are prepared by solid state reaction and their electrocaloric behaviors at room temperature are characterized. When the content of silver is around 0.2 wt%, the electro-caloric effect and adiabatic temperature changes are the highest. The results show that heat exchanges related to electro-caloric energy conversion and adiabatic temperature changes increase with increasing polarization of these ferroelectric ceramics. The ceramics are found to be very promising in energy conversion and materials engineering applications.