  We present results of observations of the transient X-ray pulsar V0332+53
performed during a very powerful outburst in Dec, 2004 -- Feb, 2005 with the
INTEGRAL and RXTE observatories in a wide (3-100 keV) energy band. A cyclotron
resonance scattering line at an energy of ~26 keV has been detected in the
source spectrum together with its two higher harmonics at ~50 and ~73 keV,
respectively. We show that the energy of the line is not constant but linearly
changes with the source luminosity. Strong pulse profile variations, especially
near the cyclotron line, are revealed for different levels of the source
intensity. We discuss the obtained results in terms of the theoretical models
of X-ray pulsars.
