  Hot stars emit large amounts of X-rays, which are assumed to originate in the
supersonic stellar wind. Part of the emitted X-rays is subsequently absorbed in
the wind and influences its ionization state. Because hot star winds are driven
radiatively, the modified ionization equilibrium affects the radiative force.
We review the recent progress in modelling the influence of X-rays on the
radiative equilibrium and on the radiative force. We focus particularly on
single stars with X-rays produced in wind shocks and on binaries with massive
components, which belong to the most luminous objects in X-rays.
