A channel electrode photo-transient experiment is described for the mechanistic characterization of photo-CE processes. This involves monitoring the transport limited current due to the discharge of a photo-generated electroactive species immediately following the stepwise application of light to the system. The theory of the experiment is given and a working surface presented which allows the analysis of experimental transients regardless of the cell geometry or solution flow rate used in their measurement. The approach is applied to the photo-electrochemical oxidation of the aminocarbene complex [(eta(5)-C5H5)Fe(CO){P(p-Tol)(3)}{=C(NHMe)(Me)}]BF4 in acetonitrile solution at a platinum electrode. The process, in the presence of light of wavelengths near 330 nm, is confirmed to be of the photo-CE type.