The R^2-gravity contribution to the energy loss of a hot plasma due to gravitational bremsstrahlung is calculated in the linearized theory on the basis of classical Coulomb scattering of plasma constituents in small-angle scattering approximation. The explicit dependence of the gravitational luminosity on the plasma temperature is derived and its relevance to the Einstein gravity is demonstrated. The result, when applied to the Sun as a hot plasma, shows very good agreement with available data.
