A multi-phase polycrystalline microporous manganese dioxide (MnO2) photocatalyst for light-induced water splitting and hydrogen generation is performed via a redox reaction under various hydrothermal conditions. By tuning the precursor concentrations down to 0.1 M, two kinds of Mn-O functional groups, including pyrolusite structures at 416, 433, 455, 609 and 646 cm(-1) and ramsdellite structures at 466 and 576 cm(-1), can be obtained by FT-IR. Morphological and phase characterizations are also examined by FE-SEM and XRD techniques, respectively. A series of peaks, corresponding to planes (110) and (200) of our sample can be indexed as a beta-MnO2 crystal with a corresponding lattice spacing of 3.11 angstrom and 2.19 angstrom. In particular, a significant enhancement of light-induced hydrogen generation by water splitting has been observed at a Pt-MnO2/C photocatalyst with an optimum hydrogen generation rate of 2261 p mol g(-1) h(-1) due to the improvement of electro-oxidation of methanol aqueous solutions, compared to a Pt-TiO2/C photocatalyst. The photoelectrochemical measurement also indicates that the multi-phase polycrystalline macroporous MnO2 photocatalyst can indeed effectively inhibit CO poisoning, help CO re-oxidation in the cocatalyst surface and maintain the catalyst's surface area in methanol oxidation and hydrogen generation efficiency. (C) 2012 Elsevier B.V. All rights reserved.