This paper describes various types of electron emitters that have been tested under conditions of interest in gas laser operations. In general, where "nonreactive" gases are used, some form of the BaSrO cathode will meet many requirements. Several matrix structures containing BaSrO are described that will stand up better under adverse conditions (ion bombardment, envelope poisoning) than the conventional sprayed cathode. Several hot hollow cathodes for use at high (15-100 amperes) currents were studied and are discussed. With reactive gases, such as O2, CO2, H2O, a BaZrO3cathode has been found to be very useful. This cathode is unique in that it emits better in an oxidizing atmosphere than it does in either an inert gas or vacuum.