The solvent-free production of edible oils from oilseeds is steadily gathering more importance. Therefore, gas-assisted pressing is an innovative process. Knowlegde of the diffusion kinetics of the gas is essential in order to optimize the process. In this paper experimentally obtained molecular diffusion coefficients of CO2 in pure rapeseed oil as well as effective diffusion coefficients of CO2 within the oil of oil-bearing rapeseed presscake are presented. The acquired diffusion coefficients are compared to literature correlations and adjustments are presented. Comparison of molecular and effective diffusion coefficients resulted in an diffusion resistance factor of the surrounding solid of 2.1.