Abstract: Scheelite-type, La x Ca1−x MoO4+δ electrolyte powders, are prepared by the sol–gel process. The crystal structure of the samples is determined by employing the technique of X-ray diffraction (XRD). According to XRD analysis, the continuous series of La x Ca1−x MoO4+δ (0≤ x ≤0.3) solid solutions have the structure of tetragonal scheelite. Their lattice parameters are greater than that of the original sample, and increase with increasing values of x in the La-substituted system. Results of sinterability and electrochemical testing reveal that the performances of La-doped calcium molybdate are superior to that of pure CaMoO4. La x Ca1−x MoO4+δ ceramics demonstrate higher sinterability. The La0.2Ca0.8MoO4+δ sample that achieved 96.5% of the theoretical density was obtained after being sintered at 1250°C for 4h. The conductivity increases with increasing lanthanum content, and a total conductivity of 7.3×10−3 Scm−1 at 800°C could be obtained in the La0.2Ca0.8MoO4+δ compound sintered at 1250°C for 4h. [Copyright &y& Elsevier]