The enhanced photocatalytic performance of Se-/In-doped TlAsS2 to generate hydrogen from water splitting is investigated based on the first-principle density functional theory calculation with meta-GGA TPSS. Three structures, namely, pristine TIAsS2 and substitutions of S with Se and Tl with In, are considered. Their geometrical lattices are fully optimized and their electronic and optical properties are calculated to evaluate the photocatalytic efficiency for hydrogen generation. Results show that the three structures can be used for solar energy photocatalysis to generate hydrogen from water splitting. Moreover, the Se-and In-doped atoms can strengthen the absorption coefficient within the visible light range. Therefore, these structures are promising catalysts for generating hydrogen from water splitting through solar energy photocatalysis. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.