An attempt was made to develop perchlorate-selective coated graphite electrode based onrncrystal violet using 1-chloronaphthalene as plasticizer. The electrode prepared by coating crystalrnviolet-perchlorate ion association in 1-chloronaphthalene both as the plasticizer and the solventrnwith a PVC matrix on a graphite rod was found to give a Nernstian response to perchlorate in arnwide concentration range. Proper response of the electrode was observed in test solutions madernin 0.1 moleL-1 potassium nitrate solution. The linear range, slope, and detection limit from thernplot of E vs log [ClO4rn-] were found to be 1.0 x 10-5-1.0 x 10-1 mol L-1, 58Â±1.5 mV/decade andrn3.16 x 10-6 mole L-1 perchlorate respectively. The electrode was also used to detect periodaternwith linear range, slope and detection limit of 1.0 x 10-4-1.0 x 10-2 mol L-1, 57Â±1.5 mV/decadernand 5.7 x 10-5 mole L-1 periodate respectively. The response time of the electrode was found tornbe < 20 s for concentrations higher than 1.0 x 10-4 M and the electrode functioned properly forrnfour weeks. The effect of the amount of the electroactive ion pair was also studied and it wasrnfound that electrode prepared from 20-30 mg of the crystal violet perchlorate was chosen withrnthe best response. The effects of diverse ions on the electrode response to perchlorate werernstudied and the potentiometric selectivity coefficients were evaluated. The electrode was foundrnto be highly selective to perchlorate and periodate. The analytical application of the electrodernwas extended to the direct determination of perchlorate and periodate and to the indirectrndetermination of ethylene glycol, glycerol, glucose and mannitol via periodate oxidation.rnKEY WORDS: Ion selective electrode (ISE), coated graphite electrode (CGE), ethylene glycol,rnglycerol, glucose and mannitol.