Abstract
Recent data from OSSE on CGRO and SIGMA on GRANAT challenge the non-thermal interpretation of the origin of the high energy emission of AGNs, showing that the hard X-ray spectra of several Seyfert AGN are steep like those of Galactic black hole candidates. Thermal models are therefore favoured. Two–phase models, in which a hot corona is placed above a relatively cold accretion disk can account for the observed X–ray spectra and the correlated variability in the UV and X–ray bands. Cold matter, both in the vicinity of the nucleous, and located further away in the torus surrounding the nucleous, may modify substantially the spectrum with important consequences on the expected variability and spectral shape.
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