The charge-transfer kinetics of photoinduced hydrogen evolution on p-Si(lll) in 1M HF has been investigated by intensity modulated photocurrent spectroscopy (IMPS) and by the new technique of photomodulated microwave reflectivity (PMMR). A comparison between both techniques is outlined. Hydrogen evolution was found to be a slow reaction that is first order with respect to Light intensity The reaction rate is virtually independent of the electrode potential over a wide range of the applied potential. The rate is also largely independent of the pH of the solution, but it seems to depend on surface properties. The surface recombination rate changes only very slowly with electrode potential, indicating strong Fermi level pinning of the p-Si/1M HF interface.