Electronic and structural changes induced by the charge storage reaction due to proton insertion in sputtered iridium oxide films (SIROFs) have been investigated by in situ X-ray absorption spectroscopy at the L-3 edge of iridium atoms in 1 M H2SO4. The iridium valency is shown to increase from 3 to 3.85 when the potential varies from - 0.2 to + 1 V(SCE). In XANES spectra, the white line peak height and energy position decrease with insertion. The fine structures of the spectra have been analyzed and simulated in view of structural parameter extraction. A correspondence curve is established between the interatomic Ir-O distance in the first shell and the iridium valency. A strong decrease of this distance is observed with the oxidation state of iridium accompanied by a conspicuous decrease of the Debye-Waller factor.