The construction and operation of a high‐sensitivity photoelectron spectrometer, specifically designed for studying reactive transient species, is described. Fast data acquisition is used to minimize spectral drift problems caused by contamination resulting from species production conditions. The spectrometer is equipped with sample differential pumping to retard contamination of the electron optics and its modular design enables individual components to be readily dismantled for cleaning purposes. A microchannel‐plate (MCP)/phosphor/silicon‐intensified‐target (SIT) camera detector is used, operated under modest voltage conditions. A unique, dedicated, dual‐buffer, data interface is constructed, incorporating the use of a video window to select data. The interface can be used in a stand‐alone mode for rapid data examination, when optimum spectrometer conditions can conveniently be established using the detector two‐dimensional imaging capability and a standard TV monitor for assessment of line image quality. Preliminary results show reductions in data‐acquisition times of up to 75 compared to equivalent single‐channel detector experiments. Several studies of transient species have been performed, which had proved unsuccessful on earlier generation spectrometers.