Electrodes in which a support matrix, containing an @I03171@ (either cationic or anionic), a plasticizer solvent, and possibly an uncharged, @S05563@-enhancing species, forms the ion-selective @MT06878@ which is usually interposed between two aqueous solutions. The support used can be either macroporous [e.g. poly(propylene carbonate) @F02384@, glass frit, etc.] or microporous (e.g. 'thirsty' glass or @I03026@ @M03667@ material such as PVC) yielding with the ion-exchanger and the solvent a 'solidified' homogeneous mixture. These electrodes exhibit a response due to the presence of the ion-exchange material in the @MT06878@. The solvent-@M03667@-@MT06878@ is an example.