A 1.8 watt cw photolytically excited atomic iodine laser at 1.315 μm is reported. This power is believed to be the highest level obtained via the cw photolysis of an alkyl-iodide gas like C 3F 7I. The enhanced laser performance was achieved using a cw microwave excited ultraviolet lamp for the laser's excitation and longitudinal flow for the removal of the quenching by-product I 2. Over an excitation length of 25 cm, an average small signal gain coefficient of 2%/cm was produced and using a stable resonator, many higher order transverse modes were observed. Its easy operation and high power may make this iodine laser very useful for the experimental testing of peripheral iodine laser technologies.