An analytical model for the description of a one-dimensional condensing flow of steam in porous media is presented. The model includes an expanded momentum balance and takes into account both compressibility of the steam and the increase of pressure loss due to higher condensation rate or initial water filling of the porous structure. Therefore the model is suited especially for the description of high pressure and high temperature steam injection processes which are often utilized in chemical engineering. The model does not only offer the possibility for quick calculation and optimization of process parameters but also allows the calculation of time dependent temperature and pressure distributions without a numerical simulation. The model is verified by extensive experimental investigations and numerical calculations with a model previously presented in this journal. The comparison of the results shows an excellent agreement with experimental data in a wide range of steam pressures and permeabilities. It is shown that especially for high pressures or permeabilities the inertia term of the momentum balance has to be taken into account for precise calculations.