In this work, NaTaO3 compounds doped with 1 M% of La and Sin, were prepared by the sol-gel (SC) method and solid state (SS) reaction; and tested as photocatalysts on the degradation of methylene blue (MB) Under UV light. The structural characterization by X-ray powder diffraction revealed that the crystallization of the NaTaO3 phase prepared by the sol-gel method started at 600 degrees C, reaching maximum crystallization at 800 degrees C. It was determined that the presence of Sm and La retard the crystallization of the NaTaO3 phase. On the other hand, the compounds synthesized in this work showed particle sizes in the nanometric scale, as it was observed by scanning electron microscopy (SEM). The specific surface area of the compounds synthesized by the sol-gel method, showed values 4 times higher than those obtained by the solid state reaction, favoring their functional and photocatalytic performance in the methylene blue degradation. In addition, the best photocatalytic performance was shown by the NaTaO3 doped with Sm and heated at 600 degrees C, having a half-life time of 65 min. (C) 2008 Elsevier B.V. All rights reserved.