Hetrocyclic systems are one of the most important classes of organic compounds present in nature or synthesized in laboratory. These compound posses several interesting biological activity and are imployed in the treatment of various commonly occurring diseases. The biological significance of the 1, 3-oxathiolan-5-one derivative has promoted us to synthesize a series of its analogical derivative. In continuation of interest on the synthesis of 1,3- oxathiolan-5-one derivatives herein an easy, practical and efficient cost effective ,time saving procedure for the synthesis of 1,3-oxathiolan-5-one derivatives by using aromatic aldehyde, mercaptoacetic acid dehydrating/ cyclising agent. All the compounds have been screened for their antimicrobial activity against three Gram -ve bacteria (Eschericha Coli, Staphylococcus aureus and Klebsiella pneumoniae three Gram +ve(Seratia reticulata, Bacillus subtilis and Streptococcus pneumoniae) and two fungal strains (P. aeruginosa and C.albicans). In the primary screening, the compounds exhibited appreciable activity. The structures of the synthesized compounds 3a-3l have been established on the basis of elemental analysis and spectral data.