Abstract: Acoated-carbon (PVCmembrane) CdBr₄^2-ion selective electrode based on the trioctyldodecyl-tetrabromocadmiumate (Ⅱ) ion pair is described. The electrode exhibited Nernstian response for cadmium (Ⅱ) in 1M NaBr solution with a slope of 31±1mV decade over the concentration range 10^-1-10^-6Mat 25.5℃.Other performance parameters of the electrode and its application have also been reported.