A study to determine the feasibility of joining refractory hard metals to each other and to oxide ceramics by a vacuum hot press- diffusion bonding method is presented. Satisfactory joins were made in the systems zrc-zrb2, zrn-zrb2, zrc-zrn, and zrc, zrn, zrb2- al203. Each of these join assemblies contained a mixture layer, 50 wt-pct each of the two end compounds. The mixture layer, sandwiched between each end compound, enhanced bonding and smooth out the thermal expansion gradient between the two end members. Joins of zro2 to zrc, zrb2, and zrn also were made, but five intermediate grading layers were required to prevent destructive cracking of the zro2 portions. Strength and thermal shock tests showed the join areas of the zrc, zrn, zrb2 joins to be stronger and more shock resistant than the parent materials. These tests were not made on the oxide joins because of the brittle nature of the oxide portions of the joined assemblies.