This study is mainly comprised of evaluating mass transfer coefficient from the volumetric flux and protein transmission data in a thin channel flow module. Dilute solutions of lysozyme. were ultrafiltered through hydrophilic membrane (cellulose acetate type) with molecular weight cut off (MWCO) of 30,000. Experiments were performed in thin channel flow (TCF10) configuration and data for transmission and volumetric flux obtained as a function of pressure and cross flow velocity. The results were analysed keeping into account the formation of Dean vortices and it was seen that the presence of Dean vortices gave better performance in terms of mass transfer. The mass transfer coefficient obtained with Dean vortices was comparable with the other commercial cross flow system involving secondary flow like Taylor vortices. A new mass transfer correlation has also been presented and compared with the reported correlations in literature.