In this study, polyvinyl alcohol films incorporated with lysozyme, as active compound, and natural fibres were investigated. Various composite systems were developed to control the release of lysozyme from the matrix by using different surface treatments of the natural fibres. Specifically, the plasma enhanced-chemical vapour deposition of acrylic acid and diamond-like coating on spelt bran powders, in a particular home-made rotating plasma reactor, were studied. Moreover, a mathematical model able to describe the release kinetics of the active compound from the polyvinyl alcohol film into water was presented. To validate the model the release kinetic of lysozyme were determined. The model was successfully used to fit the above experimental data, corroborating the validity of the hypothesis made to derive it. Results showed that the incorporation of treated natural fibres to the polymeric matrix allows to obtaining a decrease of the lysozyme diffusion coefficient up to 73.5% compared to active film without fibre. (C) 2011 Elsevier Ltd. All rights reserved.