  We present the analysis of the high energy emission of the Galactic black
hole binary GX 339-4 in a low/hard state at the beginning of its 2004 outburst.
The data from 273 ks of INTEGRAL observations, spread over 4 weeks, are
analyzed, along with the existing simultaneous RXTE HEXTE and PCA data. During
this period, the flux increases by a factor of about 3, while the spectral
shape is quite unchanged, at least up to 150 keV. The high energy data allows
us to detect the presence of a high energy cut-off, generally related to
thermal mechanisms, and to estimate the plasma parameters in the framework of
the Comptonization models. We found an electron temperature of 60-70 keV, an
optical depth around 2.5, with a rather low reflection factor (0.2-0.4). In the
last observation, we detected a high energy excess above 200 keV with respect
to thermal Comptonization while at lower energy, the spectrum is practically
identical to the previous one, taken just 2 days before. This suggests that the
low and high energy components have a different origin.
