It is needless to mention that Hammett equation is ever glowing tool in Physical-Organic Chemistry . Hammett equation has emerged from the study of dissociation equilibriums of benzoic acids in water at 25 o C [1]. There were reports on the application of Hammett equation to five membered heterocycles . Several studies appeared on the application of Hammett equation to benzimidazoles . In these studies different versions of arguments presented. In halogenated benzimidazolium cations , 5(6)-halogen substituted compounds did not follow Hammett equation which is attributed to the tautomeric nature of the ring, but a satisfactory correlation is shown with 4(7)-halogenated derivatives. In the rest of the studies a brief introduction is given on the application of Hammett equation to these derivatives.