Abstract: The ofloxacin selective electrode prepared by coating the mixture of ofloxacin and sodium tetraphenylboron association complex with PVC membrane on a glass electrode is reported. The electrode gaved Nernst response to ofloxacin over the concentration range of 5.0×10^-3～5.0×10^-5 mol/L with a slope of 51.8 mV/pC. The electrode showed a high selectivity and fast response. It has been used for the determination of ofloxacin in ofloxacin injection and capsule. The procedures of this method are simple and the results obtained agree with those of high performance liquid chromatography.