In this work, a new oxide Sm2GaTaO7 with pyrochlore-related structure was successfully synthesized by conventional solid state reaction. RuO2 nanoparticles were loaded as cocatalyst onto Sm2GaTaO7 surface. X-ray powder diffraction (XRD) and Rietveld refinement characterization results revealed that Sm2GaTaO7 crystallized into a monoclinic system with space group C2/c. The band gap (E-g) was calculated by Kubelka-Munk formula, obtaining a value in the order of 4.1 eV. The Sm2GaTaO7 oxide showed a particle size around 2-3 mu m and a specific surface area of 0.5 m(2)/g. The photocatalytic results revealed that Sm2GaTaO7 was able to produce hydrogen from pure water. The hydrogen evolution activity was enhanced by using 0.2 wt.% of RuO2 amount, which exceeded 2.4 times compared with the base photocatalyst, Sm2GaTaO7. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.