  Two different models have been put forward to explain the origin of the X-ray
emission of the unusual X-ray source 1E 1024.0-5732/Wack 2134: a high-mass
X-ray binary system (HMXB) and a colliding wind binary (CWB). We present new
optical and X-ray data in an attempt to clarify the nature of this system. The
data seem to favour the colliding wind model since the optical spectra show
characteristics of both, a Wolf-Rayet and an O-type star, implying that these
two type of stars may be present in the system. The lack of coherent modulation
(pulsations) and the relatively soft and low luminosity X-ray emission seems to
exclude the presence of a neutron star as the body generating the X-ray
emission. We present the first X-ray energy spectrum of this source at energies
above 3 keV and discuss the implications of the spectral parameters obtained
from the model fitting. We comment on the fact that the iron lines in CWB are
centred at higher energies, ~ 6.6 keV, than those detected in supergiant HMXB,
where a value of 6.4 keV is found, implying that the degree of ionisation of
iron is higher in CWB.
