Membrane catalytic deprotonation of water (water splitting) has been studied on the base of a new model which suggests that water molecules are prepolarized by H+-affinited and OH--affinited fixed charged groups of membrane before their dissociation is enhanced by electric field. Introducing some anion selective groups such as Mg(OH)(2).xH(2)O or amine into a cation selective pefluorosulfonated membrane can initiate a dramatic water splitting effect and give rise to new high frequency peaks on the OH and OD stretching region of IR spectra. This supports the hypothesis that some water molecules were affected by the surrounding electrical field from the bipolar membrane-like structure. Perfluorocarboxylic membrane was also tested in a electrolytic cell and it causes HC ion fluxes much larger than Nafion-type membrane. We classify the effect as membrane catalytic deprotonation of carboxylic acid group.