A semi-empirical model of the soft X-ray source associated with solar flares is presented, based on the results of the two temperature analysis of OSO-5 data obtained by Herring and Craig (1973). The model makes use of a jet of plasma rising from the solar surface as the basic origin of the soft X-ray emitting region, and gives rise to a cool region caused by randomisation of the jet, and a hot region caused by a shock front. Two different geometries are examined, and the model allows flow velocities and electron densities to be calculated.