Ajwain is one of the medicinal plants, which the highest composition is thymol, as a strong antioxidant respect to the obtained chromatograms of GC/MS. The antioxidant activity of the Ajwain is measured by square wave voltammetry method and cyclic voltammetry method and 2, 2-Diphenyl-1-picrylhydrazyl (Dpph) method in at the specific concentrations of 1%, 1. 5%, 2% and 2. 5% and constant pH. The results of the present study indicated that the antioxidant activity of Ajwain obtained from cyclic voltammetry and square wave is almost equal to the results of the Dpph method, which can be used to measure the antioxidant activity. Compared to Dpph method, electrochemical method involves a number of advantages such as simplicity, cheap operating costs, fastness, low amount of solvent, and no need for chemical reagents. Furthermore, based on the results obtained, the square wave method includes a higher sensitivity and accuracy than cyclic voltammetry method and Dpph method.