  We show that the so-called Gayley-Owocki (Doppler) heating is important for
the temperature structure of the wind of main sequence stars cooler than the
spectral type O6. The formula for Gayley-Owocki heating is derived directly
from the Boltzmann equation as a direct consequence of the dependence of the
driving force on the velocity gradient. Since Gayley-Owocki heating deposits
heat directly to the absorbing ions, we also investigated the possibility that
individual components of the radiatively driven stellar wind have different
temperatures. This effect is negligible in the wind of O stars, whereas a
significant temperature difference takes place in the winds of main sequence B
stars for stars cooler than B2. Typical temperature difference between
absorbing ions and other flow components for such stars is of the order 10^3 K.
However, in the case when passive component falls back onto the star the
absorbing component reaches temperatures of order 10^6 K, which allows for
emission of X-rays.
  Moreover, we compare our computed terminal velocities with the observed ones.
We found quite good agreement between predicted and observed terminal
velocities. The systematic difference coming from the using of the so called
"cooking formula" has been removed.
