In the present study, a series of substituted 2-(1H-benzimidazol-2-ylsulfanyl)-N-phenylacetamide was prepared. The synthesis of titled compounds from starting material unsubstituted 2-mercapto benzimidazoles was prepared from o-phenylenediamine and carbon disulfide in presence of KOH in single step. 2-mercapto Benzimidazole on reacting with N-substituted-α-chloroacetanilides yield different derivatives of Benzimidazole. The structure of new compounds  prepared  during  present  investigation  have  been authentically established by their IR,1H NMR and Mass spectral studies. The antibacterial and antifungal activities of thiadiazole derivatives also reported. Some of these derivatives exhibit significant antimicrobial activity. Key words: 2-mercapto benzimidazoles, phenylacetamide, antibacterial, antifungal.