This thesis carried out a detailed study of thin-film gated photocathodes. Energy distribution curves (EDC) and angular distribution curves (ADC) of photoemission from gold thin films were first studied theoretically and experimentally to understand and model the emission characteristics from thin-film photoemitters. A theoretical model for gated photocathodes based on these EDC and ADC results was developed to address the operational principles and to calculate currents as a function of gate voltage for a variety of conditions.