To　clarify　the　nature　of　different　photocatalytic　activities　between　niobate　and　tantalate,　a　comparative　study　of　the　water　splitting　into　H-2　over　strontium　niobate　and　tantalate　was　performed.　These　isostructural　photocatalysts　were　prepared　by　a　facile　and　simple　hydrothermal　reaction　and　characterized　by　powder　X-ray　diffraction　(XRD),　N-2-sorption,　UV-Vis　diffuse　reflectance　spectra　(UV-Vis　DRS),　and　transmission　electron　microscopy　(TEM).　The　effects　of　crystal　structure,　Brunauer-Emmett-Teller　(BET)　surface　area,　photoabsorption　performance,　morphology,　and　electronic　structure　are　discussed.