The kinetics of charge transfer at an electrode modified with a submonolayer of CdS nanoparticles is considered using intensity modulated photoelectrochemical spectroscopy (IMPS). First, the method of preparing an electrochemically addressable layer of CdS nanoparticles is detailed. Then a model of charge transfer from nanoparticle-modified electrodes is developed, and equations for the AC photocurrent are derived. Excellent agreement between the experimental and theoretical responses for an electrode coated with nanoparticles of approximately 5-nm radius is obtained. It is demonstrated how rate constants for both hole and electron transfer from semiconductor nanoparticles may be determined.