Poly(vinyl chloride) based membranes of 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene diperchlorate and 3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene diperchlorate with dibutyl phthalate (DBP) and dioctyl phthalate (DOP) as plasticizing solvent mediator show a Nernstian response for Cu2+ ions over a wide concentration range (1 × 10–5–1 × 10–1 mol l–1) between pH 1.9 and 5.2. These electrodes have been found to be chemically inert and of adequate stability, with a response time less than 30 s. The electrodes are selective over a large number of cations, including HgII, and anions such as Cl– and Br– cause no interference. These electrodes work satisfactorily in partially non-aqueous media and have been used as indicator electrodes in potentiometric titrations of Cu2+ with EDTA.