The extraction kinetics of molybdenum(VI) with trialkyl amine (N235, R3N, R = C8–C10) dissolved in heptane has been investigated by constant interfacial cell with laminar flow. The stiochiometry and the equilibrium constant of the extracted complex formation reaction between Mo(VI) and N235 are determined. The influences of stirring speed, temperature, concentrations of extractant and chlorine on the extraction rate has been studied. It can be concluded that the mass transfer process is a mixed chemical reaction - diffusion controlled. The extraction rate equations and the rate-determining step have been obtained under the experimental conditions by predictions derived from interfacial reaction models. Based on the approximate solutions of the flux equation, diffusion parameters and thickness of the diffusion film have been calculated.