Mesoporous CdS nanoparticles with an average pore size of 54 angstrom and a particle size of 4-6 nm have been prepared by template free ultrasonic mediated precipitation at room temperature. The as prepared particles have been characterized by UV-vis spectroscopy, XRD, N-2 adsorption-desorption isotherms, SEM and TEM techniques. The photocatalytic hydrogen production activity for the pure, noble metal loaded and supported mesoporous CdS has been studied. The photocatalytic activity has been compared with bulk and nanosize CdS prepared in our earlier studies. Among the prepared catalysts, Pt metal loaded mesoporous CdS shows highest hydrogen production rate of 1415 mu mol/h/0.1 g catalyst. In the case of supported systems, irrespective of the particle size the basic MgO support shows higher activity than alumina support. (c) 2007 Elsevier B.V. All rights reserved.