Novel polyethylene and polypropylene foils were prepared by incorporating a thermochromic composite into the polymer matrices by extrusion technology. The composite is homogeneously embedded in the polymer. Detailed investigations on the optical and surface properties of the prepared Polyolefin foils are reported. The investigations include the concentration and temperature dependence of the ultraviolet-visible spectra as well as the determination of the surface tension by contact-angle measurements. A linear relationship between the concentration of the composite and the absorption intensity of the foil has been found. In contrast to polyethylene in polypropylene no migration process was observed under the used condition. (c) 2005 Wiley Periodicals, Inc.