A LaMnO3/CdS nanocomposite was developed as a new type of visible light sensitive photocatalyst that can produce hydrogen from water containing electron donors. The nanocomposite catalyst, prepared by a reverse micelle method, was found to show high photocatalytic activity, as compared to that of CdS; on the other hand, LaMnO3 showed no photocatalytic activity. The proposed energy diagrams for the LaMnO3/CdS composite, based on the results obtained from photoemission yield measurements, suggest that photogenerated holes in the valence band of US could move to that of LaMnO3, thus separating photogenerated charge-carriers and improving the activity. (C) 2003 Elsevier Science B.V. All rights reserved.