Disc and toroidal shaped samples of composites made from powders of Na-beta -alumina and tin-stabilised tetragonal zirconia by conventional mixing and sintering processes have been used to establish data on the effect of the zirconia on the sintering efficiency, the mechanical strength, hardness and fracture toughness. These data have been compared to the results obtained when the beta -alumina powder was first pre-sintered and then infiltrated with solutions of zirconium salts or suspensions of the tin-stabilised tetragonal zirconia. The results indicate that significant improvements to the mechanical properties can be made when the zirconia is introduced via an organometallic salt dissolved in an organic solvent. For the conventionally made samples the strength and toughness peak at 15 wt% zirconia addition. Sample densities in excess of 97% are achieved by pressurless sintering at temperatures up to 1600 degreesC.