Carbon dioxide is an active constituent of modified atmosphere packaging of several foods. After packaging the carbon dioxide will equilibrate between the food and the gas phase to an extent depending on the carbon dioxide solubility in the specific food product. A mathematical model is developed for prediction of the resulting changes in solubilised carbon dioxide, headspace carbon dioxide partial pressure and headspace gas volume caused by this equilibration process. This model is the first one utilizing experimentally derived solubility coefficients for food materials, and furthermore it takes into consideration any initial content of carbon dioxide present in the food. The model is validated through a packaging experiment with semihard cheese, and its usefulness as a MAP optimization tool is demonstrated. (C) 2008 Elsevier Ltd. All rights reserved.