Turbulent spherical accretion onto massive black holes (Mapprox.10/sup 6/--10/sup 9/ M/sub sun/) is considered. Temperatures of the order of 10/sup 9/--10/sup 10/ K are found in the inner zone where the synchrotron frequencies are 10/sup 13/--10/sup 14/ Hz. If the optical depth of the hole atmosphere is tauapprox.1, Comptonization can produce a power-law spectrum of index approx.1 from the synchrotron frequencies up to medium X-rays. If tau> or approx. =1, convection of radiation into the hole becomes important at small radii, reducing the efficiency of emission. The results are briefly compared with the observations.
