9,10-Bicyclo-3-substituted-pyrazine-2-(1H)-one was prepared by mixing substituted  aromatic diamine and 2-oxo-2-substituteted acetic  acid in aq. HCl and then stirred at 400Cfor 4 hrs. Progress of the reaction by the formation of thick solid & it was monitored  by TLC ( ethyl acetate /Hexane ,1:1) After the completion of the reaction, the solid product was filtered, washed with the water and dried .The crude product was purified by dissolving in hot aqueous NaOH followed by neutralization with acetic acid. The isolated product was recrystalised from  methyl isobutyl ketone. The compounds thus synthesized have been characterized by physical and spectral data. All of these titled synthesized compounds have been screened for antimicrobial study and  are found to possesses excellent antimicrobial activities.