In this study we had synthesized some Benzimidazole derivatives and screened for their anthelminitic activity. o-Phenylenediamine was condensed with acids in presence of Polyphosphoric acid and solvents like water and dilute hydrochloric acid. The presence of specific functional group were analysed by IR spectroscopy. The determination of structure for the synthesized compounds by NMR and Mass spectroscopy is in progress. All the synthesized compounds showed significant anthelmintic activity.