Electrokinetic cross membrane extraction of acidic drugs was demonstrated for the first time. The acidic drugs were extracted from an alkaline aqueous donor solution (300 μl), through a thin supported liquid membrane of 1-heptanol sustained in the pores of the wall of a porous hollow fiber, and into an aqueous alkaline acceptor solution (30 μl) present inside the lumen of the hollow fiber by the application of a d.c. electrical potential. The negative electrode was placed in the donor solution, and the positive electrode was placed in the acceptor solution. Optimal extractions were accomplished with 1-heptanol as the supported liquid membrane, with 50 V as the driving force, and with pH 12.0 in both the donor and acceptor solutions, respectively (NaOH). Equilibrium extraction conditions were obtained after 5 min of operation with the whole assembly agitated at 1200 rpm. Eleven different acidic drugs were extracted with recovery values between 8 and 100%, and initial data supported that electrokinetic cross membrane extraction provided repeatable data and linear response between original donor concentration and final acceptor concentration of the acidic model compounds.