The paper deals with the determination of apparent diffusivity of H2SO4, HCl, HNO3, H3PO4 and HF on the basis of the experiments carried out in a batch mixed cell with an anion-exchange membrane NEOSEPTA-AFN. The dependence of apparent diffusivity of the inorganic acid upon its concentration in the membrane has been approximated by the second degree polynomial whose coefficients have been determined with the help of models based on Fick's first and second laws. Using all the experimental data obtained at various initial acid concentrations and rotational speeds of the stirrers, it has been shown that apparent diffusivity of the inorganic acid is concentration-dependent and decreases in the series HCl, HNO3, H2SO4, HE H3PO4.