The effect of alpha-radiolysis on the behavior of heptavalent technetium has been investigated in 13 and 18 M H2SO4. Irradiation experiments were performed using alpha-particles (He-4(2+), E = 68 MeV) generated by the ARRONAX cyclotron. UV-visible and X-ray absorption fine structure spectroscopic studies indicate that Tc(VII) is reduced to Tc(V) under alpha-irradiation. Extended X-ray absorption fine structure (EXAFS) spectroscopy measurements are consistent with the presence of mononuclear technetium sulfate complexes. Experimental results and density functional calculations show the formation of [TcO(HSO4)(3)(H2O)(OH)](-) and/or [TcO(HSO4)(3)(H2O)(2)] and [Tc(HSO4)(3)(SO4)-(H2O)] and/or [Tc(HSO4)(3)(SO4)(OH)](-) for 13 and 18 M H2SO4, respectively.