A potentiometric clenbuterol-selective electrode was developed based on a conducting poly(aniline) (PA) film immobilized on a glassy carbon electrode surface and a poly(vinyl chloride)(PVC) sensing membrane containing an ion pair complex of clenbuterol(CB) with tetraphenylborate. The effects of various conditions for the electropolymerization of PA such as electrochemical method, conducting support, aniline concentration, polymer (PA) film thickness were investigated in relation to the slope and linearity of calibration graphs. The electrode exhibited a Nernstian response in the CB concentration range 1x10−1to 3.9x10−6M with a slope of 60.6mV/decade (25°C). The potentiometric selective coefficients against structurally similar drugs such as epinephrine and salbutamol were of the order of 1x10−3. The electrode was successfully applied to the determination of CB in drug formulations using the calibration curve technique and also in human urine.