Abstract: This paper reports cobalt( Ⅱ ) selective electrode and zinc(Ⅱ) selective electrode made from liquid ion exchange membrane trapped in PVC. The sensors are surface-active agent [C₁₂H₂₅N(CH₃)₂CH₃]Br-tetrathiocyanatocobaltate( Ⅱ ) ion pair and[C₁₂H₂₅N(CH₃)₂CH₃] Br-tetrathiocyanatozincate(Ⅱ) ion pair respectively. The responses correspond to Nernstian relation for cobalt(Ⅱ) selective electrode with the CO²⁺ concentration rage 10^-1-10^-4.5 moles, and for zinc(Ⅱ) selective electrode with the Zn²⁺ concentration range 10^-1-10^-5 moles. Membrane potentials are independent of pH from 1.3 to 9.1 for cobalt(Ⅱ) selective electrode and from 1.0 to 8.5 for zinc(Ⅱ) selective electrode. The life of cobalt( Ⅱ ) selective electrode is 4 to 6 months while zinc( Ⅱ ) selective electrode is 6 months.