Abstract: Anew bismuth (Ⅲ) ion-selective electrode of PVCmembrane based on the associated susbstance of quaternary ammonium salt 7402 [CH₅(C_nH_2n+1)₃N]⁺Cl^-, n = 9-11] and bismuth chloride-complex has been prepared.The electrode exhibited a linear response to the chlorobismuthate (Ⅲ) complex anions within the concentration range 5×10^-5 - 1 × 10^-1M [Bi(Ⅲ)] in 2.5N HCl solution. Detection limit is 3.5× 10^-5M. Their calibration plots have a slope of 40mVper activity decade. It seems to be that the response characteristics of the membrane electrode is better than that of coated wire electrode. The electrode mentioned in this brief report may be used as a new tool for analysis of bismuth (Ⅲ) ion.