Temperature dependence studies of adsorption of sulfuric acid species on Pt(111) and Au(111) electrodes were carried out using in situ infrared reflection absorption spectroscopy. A temperature-dependent shift of the interconversion potential between HSO4-/H3O+ and H2SO4 on a Pt(111) electrode was observed. A temperature-dependent frequency shift of the absorption bands of HSO4-; was also observed on both Pt(111) and Au(111) electrodes in the potential region where a root3 x root7 structure evolved. Modelling experiments in ultrahigh vacuum revealed that ordering of the overlayer water molecules played an important role in the frequency of the absorption bands of HSO4-.