A new kind of gas permeation membrane is developed to separate higher hydrocarbons (C3+) from permanent gases. State of the art for such gas permeation applications are membranes based on solubility selective, rubbery polymers, which offer high permeances but relatively low selectivities. The new membrane is designed to improve selectivity, and therefore, significantly reduce energy demand and size of a gas separation plant. The membrane is based on the mixed matrix concept and consists of a rubbery polymer matrix with incorporated activated carbon particles. This two phase separation layer forms a solubility selective mixed matrix membrane by combining the advantages of both materials. The separation of n-(C)4H(10)/CH4 mixtures is investigated. Based on experimental results a new concept for a transport model for mixed matrix membrane is introduced.