Ascidians are marine sessile filter feeders that belong to the phylum Chordata and class Ascidiacea. Most recently ascidians have increasingly become the target of natural products research. Ascidians are dominant organisms in marine communities and have a wide geographic distribution. The present investigation is to identify the possible chemical constituents in the extract of ascidian with the aid of FTIR and GC-MS spectral analysis. IR studies indicate the presence of aromatic ring carboxylic acid, phenols, alcohols, phosphates, esters and ethers. GC-MS chromatogram of the ethanolic extract of A. multiplicatum showed 17 peaks indicating the presence of 17 chemical constituents The prevailing compounds are 4-Butylbenzoic acid, tridec-2-ynyl ester (41.7%), 5,8,11,14,17-Eicosapentaenoic acid, meth (20.8%), Pyrrolo [1,2-a] pyrazine-1,4-dione, hexahy (13.6%), Phenol, 3,5-dimethoxy-, acetate(10.0%), Vinylbital (8.3%), 4- and Methylimidazole-5-[1,1-dimethylethanol(6.0%) which may be involved in various biological activities like anti-microbial anti-inflammatory, anti-parasitic, anti-carcinogenic etc.. A. multiplicatum contains various bioactive compounds in ethanolic extract with various activities like antimicrobial, anti-cancer, diuretic, anti- inflammatory, anti- fungal, antioxidant, pesticide and chemo protective. GC- MS study is the first step towards understanding the nature of active principles.