Proton concentration of simple binary metaphosphate glasses under a pseudo fuel cell anode reaction was investigated at 350 degrees C by utilizing an in-situ Fourier transform infrared (FTIR) spectroscopy. Proton concentrations of both MO center dot P2O5 (M = Ca, Sr) glasses increase under humidified hydrogen atmosphere and applying a direct current voltage between platinum electrodes, suggesting that a proton infiltration occurs into these glasses. Compared with CaO center dot P2O5 glass, SrO center dot P2O5 glass shows higher proton concentration at the same period of time. Structure of glass network was investigated using synchrotron radiation X-ray diffraction, P-31 magic-angle spinning nuclear magnetic resonance (MAS NMR) and FTIR (KBr method) spectroscopies. Strength of the cross-linking between phosphate chains via M2+ metal cations is correlated for the proton infiltration into phosphate glasses.