The co-alignment of two detectors of the BeppoSAX Gamma-Ray Burst Monitor (40–700 keV) with the Wide Field Cameras (2–26 keV) on-board the same satellite has permitted simultaneous detection of several GRBs in X and gamma rays and their localization with high precision. These measurements allow us also to extend the study of GRB spectra down to 2 keV and with good accuracy thanks to the knowledge of source direction. We show and discuss preliminary results of the analysis of X to gamma-rays average spectra based on a sample of 12 BeppoSAX events.