In the search for a membrane material capable of separating higher hydrocarbons from methane about 40 different polymers were tested. The most promising two, polyoctylmethylsiloxane (POMS) and polytrimethylsilylpropyne (PTMSP), are compared in this article to the standard material polydimethylsiloxane (PDMS). The transport properties were investigated dependent on the process parameters temperature, feed pressure and feed composition under mixed gas conditions. It was possible to improve the separation performance by means of the selectivity from 5 to > 12 at acceptable fluxes.