The results of an optimization procedure performed for a continuous wave rf excited sealed CO2waveguide laser are presented. Parameters that affect laser performance, such as the excitation frequency, the gas pressure, and composition, as well as the electrode temperature and different kinds of circuit losses have been analyzed. An output power of 41 W (17.7 kW/l) with an efficiency of 12% has been obtained from an optimized laser with an active length 37 cm.