A process of simultaneous cell disruption and aqueous two-phase extraction demonstrated improved product yield and selectivity compared with the traditional process of cell disruption followed by extraction. Addition of aqueous two-phase components did not decrease the efficiency of cell disruption. Moreover, ADH, LDH and G6PDH recovery was enhanced in this new process with recovery ratios of 97%, 93% and 95%, respectively. Cell disruption kinetics were established based on a new mechanism that was different from traditional first-order kinetics, consisting of the release of intracellular proteins and enzymes, the denaturation and subsequent renaturation of these proteins that may be due to the protection of the aqueous two-phase components during the cell disruption process. To account for this, the kinetics parameters were calculated, and the experimental data were regressed. The resulting kinetic model could provide a better fit for the experimental data with a correlation ratio of 99% (for total protein), and led to insights into the differences between the new process and the traditional one. (c) 2005 Society of Chemical Industry