This paper describes a 1 kW average power soft x-ray source for application to sub-micron lithography. This source will be capable of 1 second resist exposure times, assuming 15 mJ/cm2 resist sensitivity, with feature sizes < 0.18 micron. The source is based on the X-Pinch, a pulsed plasma soft x-ray source which was initially developed at Cornell University for lithography. Experiments have been performed to characterize the radiation emitted from magnesium (Mg) wire X-Pinch plasmas using an 80 ns, < 500 kA pulse. Applied Pulsed Power has designed and is building a 1 kW average power soft x-ray source using the X-Pinch and a 40 pulse/second (pps), 500 kA/pulser. This system is designed to deliver 25 mW/cm2, after the attenuation due to a protective beryllium (Be) foil filter and the lithography mask, to a wafer located 56 cm from the source. This paper summarizes the experimental results and discusses the implications of these test results for microlithography applications. The design of the 1 kW source is described, including the pulser, 40 pps wire array loader, and the debris shielding. Results of initial system testing are presented.