A series of some novel benzimidazole was synthesized and evaluated for antimicrobial activity. The reaction of ophenylenediamine with dicarboxylic acid(malonic acid, succinic acid, salicylic acid, phthalic acid) yield 2- substituted-benzimidazoles.The title compounds were synthesized by treating 2-substituted-benzimidazole with benzoyl chloride and sodium hydride.Their structures were confirmed by IR,1H-NMR and 13C-NMR Antimicrobial activity against Pseudomonas aeruginosa was studied for the synthesized compounds.