Abstarct: In the first section, a simple and rapid method for captopril determination has been described baxsed on irreversible electrochemical oxidation of captopril at glassy carbon electrode (GCE) using cyclic voltammetry technique. The anodic peak was observed at 0.19V (pH=5.0), following potential cycling in the potential range from -500mV to 500mV vs. Ag/AgCl reference electrode. The linear response was obtained in the range of 10µM-1mM. The limit of detection was found to be 6.7µM. This method specially is proper for determination of captopril in tablets dosage and urine sample. In the second section, a simple and rapid method for glutathione determination has been described baxsed on electrochemical oxidation of 1,4-diaminobenzene as a mediator at glassy carbon electrode (GCE) using cyclic voltammetry technique (phosphate buffer, pH=6). The anodic peak at 0.25V was increassd in the presence of glutathione. So, we use 1,4-diaminobenzene as mediator for determination of glutathione. The linear response was obtained in the range of 5µM-600µM. The limit of detection was found to be 3.8µM.