Abstract : Solid oxide fuel cell, which can transfer chemical energy into electrical energy directly, is treated as a method to solve the global energy crisis because of its high conversion efficiency and environmental friendship. In recent years, apatite-type lanthanum silicate (La9,33+x(SiO4)6O2+3x /2 ) has been developed as a electrolyte materials for the IT-SOFC. It is possible to improve the electrical properties by doping in Si4+ sites. Among these materials, La10Si5.8Mg0.2O26.8 represents good electrical property. The objective of this study is to investigate the preparation of the electrolyte La10Si5.8Mg0.2O26.8 by plasma spraying and trying to prepare the complete solid oxide fuel cell with this electrolyte. The material La10Si5.8Mg0.2O26.8 was synthesized from the oxides (La2O3, SiO2 and MgO) by the solid-state route for its use during the thermal spraying using optimized sintering parameters. The fabrication of coating La10Si5.8Mg0.2O26.8 by plasma spraying (APS, LPPS and VLPPS) was investigated to find methods of preparing the electrolyte La10Si5.8Mg0.2O26.8 of solid oxide fuel cell. The complete and planar cell with electrolyte La10Si5.8Mg0.2O26.8 supported by the Ni/Al2O3 cermet was prepared by thermal spraying. The electrical performances of cells were measured at temperatures from 600 °C to 900 °C.