This paper is concerned with studies of the absorbance spectrum of an electrode modified with a submonolayer of cadmium sulfide nanoparticles. It is shown that the absorbance is potential dependent; a near band-edge bleaching is reported at negative potentials. The bleaching closely resembles that reported in radiolysis and nonlinear optical studies of CdS nanoparticles. Photocurrent investigations performed in conjunction with these absorbance studies indicate that the bleaching occurs only when electrons are injected into the conduction band of the nanoparticles and that charge transfer to surface states does not affect the absorption. The significance of the results is discussed with reference to the various models of absorbance bleaching in semiconductor nanoparticles.