The solubility of hydrogen in (Mg0.93Fe0.07)O was studied from 5 to 25 GPa at 1200¿C under oxidizing conditions, using FTIR spectroscopy on quenched single crystals. OH solubility increases with increasing pressure, concomitant with a decrease in ferric iron content. This result suggests that under lower mantle conditions, the charge neutrality condition could change from Me¿> = 2Me> to <(OH)O¿> = 2Me>, which would have important implications for the rheology of that region. The OH solubility data are well explained by incorporation of H as isolated hydroxyl groups via reduction of ferric iron. The amount of H incorporated at 25 GPa and 1200¿C is ~100 H/106 Me (Me = Mg, Fe), i.e. ~20 ppm wt H2O, under water-saturated conditions. When integrated over the entire mass of the lower mantle, these 20 ppm wt H2O amount to about 7.3 ¿ 1018 kg H2O, a storage capacity of ~0.5% of the ocean mass.