| Soy-sauce flavored pickled-cucumber is one of the popular ethnic food consumed in Taiwan. Desalting plays a key role in the process. In the process, a great amount of fresh water is used such that the potential of environmental impacts is increasing. Differential extraction methods are applied in the desalting process, which are not common practices used in other industries. Engineering analysis of a differential extractor is not easy to find in the literature. Mass transfer during desalting process was studied, both diffusivities and distribution coefficients of salt in the pickled cucumber were experimentally obtained. A mathematical model for differential extraction was developed. Laboratory scale desalting process was studied, the results were compared to data that predicted by the mathematical model. The extraction efficiencies obtained by experimental studies were closely predicted by the mathematical model. As predicted by the mathematical model, differential extraction was favorite at stripping rate lower than 2, but at high stripping rate, differential extraction was quite unattractive.