Abstract: The electrochemical behavior of omeprazole on a glassy carbon electrode was investigated by cyclic voltammetry and differential pulse voltammetry. It was found that omeprazole would give a sensitive oxidation peak at +0.74 V in the HAc-NaAc buffer solution (pH 5.10) under the Differential Pulse Voltammetric (DPV) mode. The peak current was linear with the concentration of omeprazole in the range of 1.0~20 mg L-1. Based on which, a DPV method for determination of omeprazole with the detection limit of 0.19 mg L-1 has been developed. The proposed method has been used for determination of omeprazole concentration in omeprazole enteric-coated tablets, the recovery was found to be in the range of 99.3~102%. The mechanism for this electrochemical reaction at the glassy carbon electrode was also discussed in this study.