Abstract In this paper, experimental data on the diffusion of quinidine sulphate through a polydimethylsiloxane film containing SiO 2 filler are reported at pH = 1.18, 4, 7.6, 8, 10 and 11; all at T = 37°C. When these data are correlated with the theoretical equation of Part I for large times, a least squares procedure gives the values of the permeability and of the fraction of quinidine adsorbed onto the filler as a function of pH. The quinidine flux is compared with that in a glass porous disc cell. The behaviour of the two ceils considered is similar only for higher values of pH. The adsorption of quinidine onto the SiO 2 phase leads to permeabilities quite different from those obtained from simpler models.