  Superfluidity of spatially separated electrons and holes and unbalanced
two-layer electron system in high magnetic field is considered.
  The temperature of the Kosterlitz-Thouless transition to a superfluid state
is obtained as a function of magnetic field and interlayer separation. The
equation of state for magnetoexciton system in quasi-classical regime is
analyzed. The transition from excitonic phase to electron-hole phase is
considered.
  Possible experimental manifestations of the predicted effects are briefly
discussed.
