Disclosed are (1) a titania-zirconia powder having at least a part of the zirconia solid-dissolved in the titania crystalline phase or at least a part of the titania solid-dissolved in the zirconia crystalline phase, (2) a titania-zirconia powder containing 3 to 30 wt % of zirconia and 0.5 to 10 wt % of yttria and containing less than 20 wt %, in total, of at least a complex oxide having a composition of ZrTiO4 or (Ti,Zr) O2, monoclinic phase zirconia, and tetragonal phase zirconia, wherein the titania-zirconia powder comprises an anatase phase, and which retains a specific surface area of 34 m2/g or more after heat-treated at 900° C. for 5 hours in the air, and (3) a titania-zirconia powder wherein the titania-zirconia powder (1) or (2) having an average particle size of 1 &mgr;m or smaller is mutually dispersed with an alumina powder; and processes for producing the powders are disclosed.