Model solns. contg. Zn(II) 0.31, H+ 0.55, Cl-5 M, were extd. with kerosene-dild. tri-n-butyl phosphate (TBP). A Lewis cell (fixed contact area) and a single-drop method were used. Equil. isotherms were detd. conventionally in the dispersed system. In the aq. soln., Zn(II) existed 92% as ZnCl42-. Mass fluxes and mass-transfer coeffs. were detd. by using the boundary layer theory. The complexes transferred into the org. phase were ZnCl(2 center dot)2TBP and ZnCl2 center dot 3TBP. The reaction was first order with respect to Zn(II) and the extn. rate const. was 1.77(+/- 0.28)center dot 10(-4) dm(3)/ (mol center dot s).