Photocathodes with relatively low energy spread (< 0.5 eV) are required for electron sources in several applications including single and multiple electron beam inspection and lithography tools and free electron lasers. CsBr based photocathodes have been shown to be very robust and capable of operation at high current density (>150 A/cm(2)) with very long lifetime (approximately hundreds of hours/spot). Experimental results of the photoelectron energy spread obtained in CsBr films deposited on both metal and InGaN substrates will be presented in this paper.