Effect of n-propylamine addition on the stability of oil-in-water emulsions containing a triisocyanate soluble in the oil phase was investigated. The oil component was di-n-butyl phthalate(DBP) containing Aerosol-OT as an emulsifier. The drop size change with time was measured to estimate the emulsion stability. It was found that the addition of n-propylamine after emulsification accelerated the coalescence of drops for the emulsion with a triisocyanate. The effects of temperature, amine concentration, polarity of oil phase and AOT concentration were established in this study.