The proton diffusion coefficient for both fresh and heat-treated (140 and 230°C, respectively) α and β-PbO2 electrodes was estimated at room temperature using Galvanostatic Intermittent Titration Technique (GITT). PbO2 samples were prepared by electroformation of cured plates. HSbO3·xH2O with a conductivity of 3.29×10−3 Ω−1 cm−1, was used as solid protonic conductor (SPC) electrolyte. It was found that when structural water is removed, the capacity of both α and β-PbO2 electrodes decreases and the ohmic drop increases. The departure of structural water affects considerably the value of proton diffusion coefficient.