Abstract: Instantaneous wall transfer of a gas plug rising in a vertical short tube is measured by using electrochemical method. Compared to the results based on hydrodynamic models of developed slug flow, plug rising in a short tube is under an undeveloped condition; wall stress and Sh number follow an analogous pattern, whose minimum appears at the nose and maximum appears at the bottom of gas plug. Wall stress and Sh number in falling film agree with model prediction developed by Zhang.A profile of momentum and concentration boundary layer in liquid slug is presented in this paper, which shows that falling film has little influence on wall mass transfer has significant influence on wall stress.