A direct nonaqueous potentiometric determination of glaphenine hydrochloride and glaphenine authentic compounds and in their pharmaceutical formulations, namely glifanan suppositories, glifanan and adalgur tablets(R)is developed. The method involves the titration with 0.1N aceteous perchloric acid after the addition of mercuric acetate in case of hydrochloride salts, using a combined glass electrode. The results of the method were compared with those of the spectrophotometric1and the alkalimetric2procedures. The method can be adopted for quantities ranging between 50 and 500 mg with an accuracy of 102 ± 1.1, 98.8 ± 0.4 and 101.2 ± 0.5 for glifanan suppositories, glifanan tablets and adalgur tablets respectively.