N-pentane has been commonly used as a solvent and can be a reliable physical blowing agent in foaming processes. Many researchers have quantified the solubility of the n-pentane in polymers by different ways. In this study a new and easy approach was proposed to measure the solubility of n-pentane in polymers. Our designed chamber consisted of a well-sealed cell cavity, equipped to a pressure gage and a temperature controller. The samples were impregnated by n-pentane in the chamber and they were weighted before and after locating in the chamber. The solubility of n-pentane in polyethylene was measured in different pressures and temperatures. In this study also the Sanchez-Lacombe (SL) equation of state was used to estimate the swelling effect of n-pentane on polymer samples. The experimental results for the solubility of n-pentane in the polymer were in a good agreement with theoretical results.