Food industry use polymers as packaging to protect and maintain high quality and freshness of the product during distribution and storage. Polymers are permeable for gases like O2, CO2 and water vapor. Simulation models for the oxygen-(OTR) and the water vapour (WTR) transmission rate through different polymers and polymers layers are developed by Norner AS. In this report, a suggestion for a model describing the diffusion of CO2 through different polymers used in food packaging, as well as a model describing the temperature dependency for permeation is evaluated. Relevant material constants have been used from experimental work, literature and from an external test-center, Innoform Testservice. The models were found from a theoretical study of the solution-diffusion model and simulated in MATLAB. The experimental equipment used in this thesis was a volumetric method and not suitable for polymers used as a gas barrier. Therefore, the models were based on material constants found from the literature and Innoform Testservice. The suggested model describes the consumption of CO2 through a single layer polymeric barrier, under steady state conditions and 0% relative humidity for different temperatures. The model can be verified using experimental values and for a more powerful model, a study using different polymers layers and the influence of the humidity should be studied.