In this work, coumarin was synthesized by Perkin reaction using salicylaldehyde, acetic acid and sodium acetate. Due to the misuse of acetic anhydride in narcotics synthesis, acetic acid was substituted for acetic anhydride in Perkin reaction. On the basis of this substitution a hypothesis was proposed that "acetic acid could be substituted as an acetylating agent in place of acetic anhydride in coumarin synthesis via Perkin reaction". In the present research project, salicylaldehyde was prepared from phenol, sodium hydroxide and chloroform for further procedure. Then four different coumarin samples were synthesized by changing the parameter of reactants proportions. From this parameter, we designed a trend of high product yield. Yields of Coumarin samples will lead towards either acceptance or rejection of the above proposed hypothesis. In the next step, these Coumarin samples were characterized by age yield (%), solubility and melting points. At last Antibacterial activities of all the four coumarin samples were evaluated against two bacterial strains; E.coli and S.aureus. As a consequence of all above, it was inferred that the yields of all coumarin samples obtained were low as compared to the yield obtained by the use of acetic anhydride in previous reports. This led to the rejection of proposed hypothesis. Among four Coumarin samples, sample-4 obtained by taking equal amounts of all the reactants had shown maximum yield, best characterization and excellent antibacterial activity. In spite of low yields obtained, the remarkable antibacterial activities of Coumarin samples have enabled us to suggest coumarin as a strong antibacterial agent and it must be employed for further applications.