Phenolic compounds have been considered for the antioxidant role and are widely used in food and pharmaceutical industries to prevent oxidative degradation and corrosion of foods and drugs. Electrochemical methods have been used in recent decades for the determination and screening of antioxidants. The advantages of this method are low cost, fast and sensitive, and the lack of need for high sample preparation. In this study, the extracts of two types of brown algae, Dina and Cystosuria, were placed at different times in darkness and light. After examining the results, the filtrate extract had a more stable antioxidant properties than the filtered extract and in the darker it was less effective than Show themselves.