The effects of ultrasonic irradiation at various pH on viscosity, gel strength, setting time, sol fraction, molecular weight distribution, reactivity with mucochloric acid and amino acid composition, of photographic gelatins were investigated. In this study, acid and alkali processed gelatins were compared for the above characteristics. Although viscosity decreased and gel strength increased, the influences of irradiation pH were not large. But sol fraction and reactivity with mucochloric acid were influenced by irradiation pH.