The acidity constants of 4,5-diphenyl imidazole, 2,4,5-triphenyl imidazole, and 2,4,5-triphenyl imidazole derivatives in nitrobenzene, acetonitrile and glacial acetic acid were determined. Perchloric acid, prepared in 1,4-dioxane, was used as the titrant for the measurement which were done in acetonitrile; perchloric acid, prepared in nitrobenzene, was used as the titrant for the measurements that were done in nitrobenzene and perchloric acid, prepared in glacial acetic acid, was used as the titrant for the measurements which were done in glacial acetic acid. The pKa values were obtained from the half neutralization potentials which were obtained from an analysis of the potentiometric titrations. The ranging of the increasing acidic strengths were determined by considering whether the compounds had a substituent on 4, 5 position or not.