A thermodynamic study of non-equilibrium, two-phase flow processes has been presented,introducing the 'non-equilibrium parameters' related with the causes for deviations from equilibrium and the advance of relaxation phenomena towards equilibrium. Taking these non-equilibrium parameters as input, a comparative parametric study of several processes may be realized and indices relative to the quality of these processes, like entropy production, temperature deviation, etc., may be obtained as output. In the present work an estimation of non-equilibrium parameters is undertaken for the specific pattern of water boiling in the post dry-out region, using available data for the vapour superheating.