The paper deals with the determination of mobility of H3O+ and Cl- ions on the basis of experiments with hydrochloric acid carried out in a batch mixed cell with an anion-exchange membrane NEOSEPTA-AFN, which have been completed by measurements of the membrane conductivity. The dependencies of mobility of H3O+ and Cl- ions upon the acid concentration in the membrane have been approximated by the second degree polynomial, whose coefficients have been determined with the help of a model based on the Nernst-Planck equation - the membrane being modeled as a homogeneous gel phase containing fixed positive charges, water molecules and mobile H3O+ and Cl-ions. Using all the experimental data obtained at various acid concentrations and rotational speeds of the stirrers, it has been found that mobility of H3O+ and Cl- ions is strongly affected by the acid concentration in the membrane.