Glucoamylase (GA) enzyme has been got wide application in the food and fermentation industries. It has been gotten second position in world’s distribution and sales of industrial enzymes. In this study, extracellular enzyme GA from Aspergillus niger , produced using solid state fermentation, was separated by nanoparticulate reverse micelles of CTAB cationic surfactant. A reverse micelle extraction cycle is basically composed of two processes: forward and backward extraction. In the forward extraction step, enzymes are transferred from the initial aqueous phase to the reverse micelles and in back extraction step, enzyme are transferred from the reverse micelles back to a fresh aqueous strip solution. The effects of surfactant concentration, pH, NaCl concentration, cosolvent concentration, phase volume ratio, and surfactant charged kind on the both steps of extraction efficiency were tested. Following single-factor experiment, the optimum extraction was achieved by response surface methodology (RSM) using central composite rotatable design (CCRD). The experimental results concluded the highest forward extraction efficiency of GA activity at pH 8, NaCl concentration 50 mM, CTAB concentration 100 mM, and cosolvent concentration 10 %. Moreover, for the maximum back extraction recovery of the enzyme, pH and NaCl concentration were obtained to be 4.2 and 417 mM, respectively. Finally by the optimization of phase volume ratio for both steps, purification factor and efficiency of enzyme recovery increased from 2.15 and 73% to 2.7 and 76%, respectively. This study demonstrated that liquid- liquid extraction by CTAB reversed micelles is an efficient process to separate and purify the GA from fermentation broth. Keywords: Nanoparticulate reverse micelles, CTAB, glucoamylase, protein purificatio