Seaweeds (Marine macroalgae) area large group of marine organisms containing important phytochemical constituents with various biological activities.They are potentially prolific sources of highly bioactive secondary metabolites, which manifest many of the therapeutic effects like anti-cancer, anti-oxidant, anti-inflammatory and anti-diabetic activities. Seaweeds are used by many Asian cultures for traditional medicine preparations. The Caulerpa peltata was collected from Rameshwaram coastal area it was shade dried, made in to powder using standardized procedure to get Caulerpa peltata Methanolic Extract (CPME). The phytochemicals and Gas Chromatography-Mass Spectrometry (GC-MS) analysis was done on prepared CPME for identifying the bioactive compounds. Phytochemical investigation suggests that the Caulerpa peltata exhibited the presence of phytochemicals like Alkaloids, Carbohydrates, Phytosterols, Saponins and Diterpenes,which may contribute to its biological activities. GC-MS analysis showed 28 variety of compounds,among which Dibutylphthalate, n-hexadecanoic acid, and 1,2-Benzene dicarboxylic acid was found in high percentage. The phytochemical studies and the compounds available in GC-MS showed that the Caulerpa peltata contain important bioactive compounds,which may have anti-microbial, anti-fungal and anti-cancer activity. Further research is needed for finding its use in development of new pharmaceutical agent and its safe consumption by human for various health benefits. © 2020 This is an Open Access article licensed under a Creative Commons license: Attribution 4.0 International (CC-BY). Published by Oriental Scientific Publishing Company.