Commercial tin dioxide powders have been subjected to mechanical treatment in order to modify their microstructure. Processed powders were then used to assembly thin film electrodes which worked as anodes in a three electrode cell to drive the oxygen evolution reaction from acid solution. Cyclic voltammetry and polarization experiments were carried out together with electrochemical impedance spectroscopy to highlight the effects of milling on the catalytic performance. The findings suggest that the mechanical processing is capable of generating a considerable amount of lattice defects. The grain boundary extension as well as the content of structural disorder increase with the processing time. The increase in both the reactive site density and extent of structural disorder results in an enhanced chemical reactivity of the assembled electrodes.