This paper is devoted to an investigation of the wear mechanisms of magnesia and yttria partially-stabilized zirconia in ceramic/ceramic and ceramic/metal sliding-contact tribological systems at high temperature. It was found that the wear of ceramics rubbed against ceramics at room temperature may be attributed to intensive plastic deformation of surfaces resulting in low cycle fatigue. The wear mechanism of ceramics rubbed against metals was by polishing and surface fracture, while that of metals was adhesive transfer of material on to ceramic surfaces.Investigation of the wear behavior of magnesia partially-stabilized zirconia rubbed against itself showed that up to three orders of magnitude increase in wear resistance can be achieved in a particular temperature range, depending on both sliding speed and the ambient temperature. XRD analysis revealed that a thermally-induced phase transformation takes place on the frictional interface.A phenomenological model is presented that provides an explanation for the wear-temperature behavior of Mg-PSZ. The model is based on the following chain of events that takes place on the frictional interface: spatial overheating of the surface areas, phase transformation of the overheated areas, cooling, volume expansion, and development of a compressive stress field in the near surface layers.