  Several colliding-wind massive binaries are known to be non-thermal emitters
in the radio domain. This constitutes strong evidence for the fact that an
efficient particle acceleration process is at work in these objects. The
acceleration mechanism is most probably the Diffusive Shock Acceleration (DSA)
process in the presence of strong hydrodynamic shocks due to the
colliding-winds. In order to investigate the physics of this particle
acceleration, we initiated a multiwavelength campaign covering a large part of
the electromagnetic spectrum. In this context, the detailed study of the hard
X-ray emission from these sources in the SIMBOL-X bandpass constitutes a
crucial element in order to probe this still poorly known topic of
astrophysics. It should be noted that colliding-wind massive binaries should be
considered as very valuable targets for the investigation of particle
acceleration in a similar way as supernova remnants, but in a different region
of the parameter space.
