Hard X-ray radiation has been detected for the first time in the Coma cluster by Beppo-SAX .
Thanks to the unprecedented sensitivity of the Phoswich Detection System ( PDS ) instrument , the source has been detected up to \sim 80 keV .
There is clear evidence ( 4.5 \sigma ) for non-thermal emission in excess of thermal above \sim 25 keV .
The hard excess is very unlikely due to X Comae , the Seyfert 1 galaxy present in the field of view of the PDS .

A hard spectral tail due to inverse Compton on CMB photons is predicted in clusters , like Coma , with radio halos .
Combining the present results with radio observations , a volume-averaged intracluster magnetic field of \sim 0.15 \mu G is derived , while the electron energy density of the emitting electrons is \sim 7 \times 10 ^ { -14 } ~ { } erg / cm ^ { 3 } .