An electrodialytic acid regeneration apparatus includes two electrodes and a stack of electrodialysis chambers arranged between the electrodes. Immediately adjacent chambers are separated from each other by alternating anion exchange membranes and cation exchange membranes selected from one of a monovalent cation exchange membrane and a proton permselective cation exchange membrane, which forms electrodialytic chambers of two types. In an associated method the first type of chamber is supplied with the spent acid solution and the second type of chamber is supplied with low ion concentration solution. Under the action of an electric potential difference applied across the electrodes, protons are transferred through the cation exchange membranes from the spent acid solution to the low ion concentration solution and anions are transferred through the anion exchange membranes from the spent acid solution to the low ion concentration solution. The low ion concentration solution, suitably recirculated through the apparatus, may be rendered as regenerated acid.