Abstract: In 0.1mol L^-1 H₂SO₄,a sensitive reduction of ketoprofen was observed.With accumulation time 40 sand scan rate 100 mV·s^-1, its peak potential is-0. 80 V(υs.Ag/AgCl).The voltammetric behavior and the electrode reaction mechanism of ketoprofen have beenstudied by linear sweep and cyclic voltammetry,etc,αn, α and the number of H+ in the electrodereaction have been determined to be 1.05,0.53 and 2,respectively. The wave is an irreversiblewave with adsorptive property, which may be applied to the determination of trace amount of ketopro-fen. The detection limits are 1.0×10^-9mol L^-1 and5.O×10-^-8mol·L^-1 for adsorptivevoltammetry and oscillopolarography, respectively.