Cladophora algal species was subjected to phytochemical and antioxidant studies. The phytochemical studies revealed that it contains flavonoids, tannins, carbohydrates/ glycosides, sterols, terpenoids, sulphates, chlorides and free from saponins and alkaloids. Also the free and combined sugars, amino acids, phenolic acids, fatty acids, hydrocarbons, sterols and minerals were analysed quantitatively. Determination of phenolic acids was carried out and the flavonoid compounds were isolated from this alga. From this study Cladophora algal species can be considered as a promising antioxidant agent.