A CW waveguide CO2 laser is designed and constructed. The laser cavity consists of a Pyrex discharge tube of 26cm length and of internal and external diameter of 3 and 4mm respectively. The waveguide tube is surrounded by a water jacket of 18mm iameter and of 23cm length..The water jacket has inlet and outlet ports for the cooling water. A 25mm diameter gold plated metallic mirror of 5m radius of curvature and of reflectivity 99.9 % is used as a rear mirror for the resonator.For the front mirror, a plane 25mm diameter mirror made of Zinc Selenide (ZnSe) and of 80 % reflectivity is used. The mirrors and the tube are held by specially made Perspex holders. Copper tubes of 5mm external diameter are used for the inlet and outlet of the gases and as electrical discharge electrodes. An electrical DC power supply is constructed to provide a 15 kV DC and 330 mA .Experiments using different compositions of gases CO2 : n: : He are performed with the ratio of 1 : 1 : 3 ; 1 : 1.5 : 7 ; 1 : 1: 8 ; 1 : 2 : 8, using different pressures . The maximum laser output power obtained for the range of pressures used was 0.55 W at 8 mbar pressures using gas composition ratio of 1 : 2 : 8