Antimicrobial films were prepared by incorporating different concentrations of tea tree essential oil (TTO) into chitosan (CH) films. Film-forming dispersions (FFD) were characterized in terms of theological properties, particle size distribution and zeta-potential. In order to study the impact of the incorporation of TTO into the CH matrix, the water vapour permeability (WVP), mechanical and optical properties of the dry films were evaluated. The properties of the films were related with their microstructure, which was observed by SEM. Furthermore, the antimicrobial effectiveness of CH-TTO composite films against Listeria monocytogenes and Penicillium italicum was studied. (C) 2010 Elsevier Ltd. All rights reserved.