The transport mechanism of protein-based bioactive compounds (a peptide fraction from whey protein concentrate, glycomacropeptide and lactoferrin), from chitosan films to liquid medium, was studied. Mathematical models were used to discuss the transport mechanism: Data from release experiments was successfully described by a model which accounts for both Fick and Case II transport - the linear superimposition model. Results show that the mechanism of transport and the effect of temperature and peptide type could be related with physical properties of chitosan films where the tested bioactive compounds were incorporated. The approach presented here allows interpretation of the phenomena involved in mass transport in the systems studied and, once extended to other systems, may contribute to an understanding of transport in hydrophilic bio-polymeric matrices. (C) 2012 Elsevier Ltd. All rights reserved.