Abstract. We report on the swelling process in gold-doped teflon-like films as a function of metal concentrations. The film thickness variation, measured in low-pressure acetone vapour using an ellipsometric technique, shows, with a range of 0.0019mbar, a linear increase in gold content. This trend disappears for metal percentages near to the percolation threshold, an effect which is also evident from the time evolution of the swelling process at constant pressure.