The aim of the present paper is to evaluate the phytochemicals, the antioxidant activity of marine algae Gracilaria corticata (G. corticata) and Spirulina platensis (S. platensis). The phytochemicals present in the selected marine algae G. corticata and S. platensis were screened and their antioxidant activities were tested. The marine algae was collected, shade dried, powdered and extracted with methanol. The presence of a variety of chemical constituents, such as saponins, phenols, glycosides, flavonoids and alkaloids were analyzed in these marine algae by TLC and HPLC method. Their antioxidant activities were studied by Fentons method and DPPH assay. Phytochemical screening showed the presence of active molecules. The selected algae is having antioxidant potential. From the study, it is clear that these G. corticata and S. platensis are the prospective sources of bioactive compounds.