A new method,-called the "oil-drop method", was developed and adapted to studing the rate of enzymatic reactions, using long chain triacylglycerols, the main physiological substrates of digestive lipases. The method is based on the variations versus time in theoil/waterinterfacial tension (Yo/w) resulting from the accumulation of water insoluble lipolytic products on the surface of a drop (1). Measurements were carried out with pure Porcine Pancreatic Lipase (PPL). This method was also used to detect Human Gastric Lipase (HGL)at low pH,since difficulties were encountered in earlier studies when measuring lipolytic activity under acidic conditions (2). The lipolytic kinetics under high hydrostatic pressure (800 and 1200 bars) were also investigated with the oil-drop method, and a specific two-fold increase in lipase activity was found to have occured. A newprototype is being developed for automatically analyzing the oil-drop profile is being developed in order to improve the data acquisition rate andthe accuracy of the measurements.