This paper discusses the dynamic interfacial tension (IFT) variation in a system containing an acidic oil in contact with an alkaline solution which may contain a preformed surfactant. A modified technique similar, in principle, to the sessile drop technique is used for monitoring the dynamic IFT which is in the ultralow range. The technique is then applied for measuring ultralow IFTs in systems consisting of acidic oils and alkaline solutions containing preformed surfactants. The effect of aqueous phase pH, surfactant concentration, and oil phase acid concentration on the dynamic IFT variation in these systems is determined by using this technique.