The total phenol content of five species of marine macro algae belonging to Chlorophyceae and Rhodophyceae were analysed for one year. Of the five species that were analysed, three species belong to Chlorophyceae and two species to Rhodophyceae. The annual mean of phenols was high in C. sertularioides followed by G. corticata, U. fasciata, E. compressa and H. musciformis. The phenols ranged from 110 to 520 μg/g among the five species. The seasonal variations in distribution was also observed in these five species. The phenols were observed high in winter season for E. compressa, C . sertularioides and G. corticata and during summer season for U. fasciata and H. musciformis. The environmental variables such as pH, dissolved oxygen, light and silicate were correlated positively at P ≥ 0.05 level with the phenols of these macro algal species. The ANOVA showed a significant variation between U. fasciata, E. compressa; U. fasciata and C. sertularioides; E. compressa and C. sertularioides at P < 0.05. The variation is also significant between G. corticata and H. musciformis at P < 0.05 level. The variations in the distribution of total phenols may be due to variation in species, sediment and surrounding water quality. All the five macro algae tested showed antioxidant activities and these algae have significantly possessed 31 to 56% antioxidant activity indicating that these species may exert potential natural antioxidant properties for various applications in industry.