  A hydrostatic and stationary white dwarf envelope model has been developed
for the study of the post-outburst phases of classical novae and their soft
X-ray emission. Several white dwarf masses and chemical compositions typical
for classical novae have been considered. The results show that the luminosity,
maximum effective temperature and envelope masses depend on the white dwarf
mass and on the chemical composition. Envelope masses for which equilibrium
solutions exist are pretty small ~10^{-7}-10^{-6} Msun, thus leading to a short
duration of the soft X-ray emitting phase of classical novae, in agreement with
most of the observations. The models presented provide a useful tool for the
determination of the white dwarf properties from observable parameters in the
X-ray range.
