The electrochemical determination of omeprazole (OMZ), a gastric acid secretion inhibitor, is described using cyclic voltammetry and square wave voltammetry (SWV) at edge plane pyrolytic graphite sensor (EPPGs). A well-defined oxidation peak was observed in SWV as a result of the oxidation of OMZ at similar to 828 mV in phosphate buffer of pH 7.2. The peak current increased linearly with the increase of concentration of OMZ in the range 1 mu M to 100 mu M and detection limit (3 sigma/b) and sensitivity were found to be 19 nM and 0.1549 mu A mu M-1, respectively. The analytical utility of developed protocol was evaluated by performing the recovery experiments in human plasma samples of patients undergoing treatment with OMZ and recovery was found in the range of 98.71-100.82%. The method was successfully used to determine the content of OMZ in enteric-coated tablets of pharmaceutical formulations of different companies and blood plasma of patients undergoing treatment with OMZ. The sensor exhibited good stability and reproducibility with relative standard deviation of +/- 2.74% and +/- 3.48%, respectively. The method is simple, reliable and precise with good stability and reproducibility. (C) 2014 The Electrochemical Society.