The knowledge of sorption equilibria of blowing agents in polystyrene (PS) is necessary for the optimization of PS foam production. The sorption equilibria were studied experimentally using a gravimetric apparatus and simulated by the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state. As chlorinated and fluorinated hydrocarbons are being phased out, alternative blowing agents are important. We place emphasis on n-pentane, as sorption data for the PS+n-pentane system are scarce in the literature. The measured n-pentane and iso-pentane sorption isotherms were used to evaluate the PC-SAFT binary interaction parameters. The sorption of CO(2), N(2) and He in PS was also studied. Cosorption of pentanes in PS was predicted and comparison of the results with our experimental data proved good performance of the PC-SAFT model. The industrially interesting sorption enhancement and inhibition effects were studied using both experimental and simulated ternary data. (C) 2011 Elsevier Ltd. All rights reserved.