The crystallinity, textural characteristics, optical absorption properties, as well as the photocatalytic hydrogen production activities of three-dimensional interconnected mesoporous In2O3/Ta2O5 composites were investigated as functions of In2O3 content (x) and calcination temperature (T). The results show that the incorporation of In2O3 endows intimate heterostructured junctions in the composites and significantly improves the thermal stability of mesopores. With increasing x, the as-prepared composites possess similar textural properties and continuously increased light absorbencies, but a maximum heterojunction area, and thus, the optimal value for the average hydrogen evolution rate (GO as well as the special surface hydrogen evolution rate ((Q) over bar (H2S)) at x = 20%. For the 20% In2O3/Ta2O5 composites prepared at different T, the special surface area decreases and the pore size enlarges with increasing T from 450 to 650 C. An obvious collapse of mesopores accompanying with remarkable crystallization occurs at 750 C. The highest (Q) over bar (H2) occurs on the sample calcined at 550 C, while the optimal (Q) over bar (H2S) appears at 750 C. This suggests that good charge carrier separation and transport properties, rapid mass transfer of reactants and gases desorption are as important as large surface area and high crystallinity for the photocatalysts. (C) 2012 Elsevier Inc. All rights reserved.