A formula for the X-ray flux from Compton-synchrotron emissivity is derived. The values of flux obtained for some radiosources taking the values of magnetic field derived from the assumption of equipartition of energy between the magnetic field and cosmic rays are well below the limits of sensitivity reached by recent measurements. However if the magnetic field is derived from the synchrotron auto-absorption theory, the values of the predicted flux are 103 larger and they could be detected.