The inactivation of the coliphage MS2 (a human virus indicator) by solar photo-Fenton at near neutral pH in carbonate buffer solution matrix was evaluated. The effects of reactant concentration (H2O2, Fe2+, Fe3+) and solar irradiance on the photo-Fenton process were studied. Specifically, the solar exposure/Fe3+ treatment showed a strong dependence on the iron concentration and solar irradiance intensity leading to complete inactivation (from 10(6) PFU mL(-1) to the detection limit) with 1 mg L-1 of Fe3+ and 60 min of solar irradiance (45 W m(-2)). The MS2 inactivation observed with the photo-Fenton process (solar exposure/H2O2/Fe2+/3+) carried out with Fe3+, was faster than with Fe2+ (detection limit achieved at 20 min and 50 min, respectively). Moreover, virus inactivation by photo-Fenton under different solar irradiance values (15,30 and 45 W m(-2)), H2O2 and Fe3+ concentrations (0.1, 0.5 and I mg L-1) and different pH values (6, 7 and 8) were evaluated. In order to validate the efficiency of the photo-Fenton process at near neutral pH on virus inactivation, the photocatalytic treatment was carried out in natural water (Lake Geneva, Switzerland) and with a human virus (Echovirus). Finally, a conceptual mechanistic interpretation was proposed regarding how solar photo-Fenton acts on viruses in water, involving the key species Fe2+, Fe3+, H2O2, solar irradiance, organic matter, and their possible reactions and interactions. (C) 2015 Elsevier B.V. All rights reserved.