Mass transfer in single porous particles is studied by measuring uptake rates in porous single particles and by modelling these rates with a non-isothermal, non-isobaric Maxwell-Stefan model. Uptake curves of carbon dioxide, methane and ethane in specially prepared activated carbon extrudates were measured in a gravimetric analyser in a broad range of temperatures, concentrations and pressures. The model describes mass transfer due to pore diffusion (bulk and Knudsen diffusion), viscous flow and surface diffusion. To identify the different types of mass transport in the porous particles two types of kinetic uptake measurements were performed: responses to pure component pressure steps and responses to concentration steps at constant feed pressure. All transport mechanisms contribute significantly to the total molar flux. Surface diffusion is an important transport mechanism at low temperatures and at small step changes in both concentration and pressure. Viscous flow is not only important in experiments with a total pressure change but also in concentration step experiments at constant total pressure.