A large molecular weight protein, alcohol dehydrogenase (ADH, 141 kDa), has been purified fi om baker's yeast using reversed micelles formed with a cationic surfactant (cetyltrimethylammonium bromide, CTAB) using the phase transfer method. Various parameters, such as pH, ionic strength and contact time of the two phases in ADH forward and backward transfer were studied. The active ADH was successfully recovered after a full forward and backward extraction cycle. The recovery of ADH activity obtained was similar to 90% and the purification factor was 3.1 for the overall process.