Novel polymeric membrane (PME) and coated glassy carbon (CGCE) perchlorate-selective electrodes based on a phosphorus(V)-tetraphenylporphyrin complex were prepared. The electrodes exhibited near-Nernstian responses over wide ClO 4 - ion concentration ranges (from 8.0x10 - 6 to 1.6x10 - 1 M for PME and 1.0x10 - 6 to 3.0x10 - 2 for CGCE) and very low detection limits (5.0x10 - 6 M for PME and 7.0x10 - 7 M for CGCE). The electrodes possess low resistances, very fast response times, relatively long lifetimes and, most importantly, good selectivities relative to a variety of other common anions. The potentiometric response of the electrodes is independent of the pH of test solution in the pH range of 4.0-10.0. The proposed sensors were used to determine perchlorate ion in water and human urine.