Abstract: Experimental studies were carried out on extraction of lactic acid from a aqueous solution using a PVDF Supported Liquid Membrane (SLM) containing 40% (v/v) trialkyl phosphine oxide(TRPO) in kerosene as a carrier. The effects of pH, lactic acid concentration, carrier concentration, flow rates of the feed and strip solutions and temperature on the flux of lactic acid across SLM were investigated. The qualitative discussion on the membrane stability was also made. It was observed that only undissociated molecules of lactic acid can penetrate through the SLM, and that the membrane soaked with 40% TROP-60% kerosene possesses a maximum transfer rate of lactic acid. The transfer rate of lactic acid is proportional to the concentration of lactic acid in the feed solution. The membrane stability can be greatly improved by presaturating the feed and strip solutions with the carrier solvent.