The removal of heavy hydrocarbons from natural gas becomes necessary to facilitate its pipeline transport and distribution, and for applications in conventional gas burners and co-generation engines. This work presents the use of silicalite membranes for this separation process. It was found that n-butane permeates preferentially over methane, due to its strong adsorption on the membrane, which hinders methane permeation. The influence of the operating conditions (temperature, sweep gas flow, gas composition, etc.) was studied experimentally. Several membranes prepared by different methods are compared. The best separations are obtained with the same pressure at both sides of the membrane and with the use of a sweep gas. Pretreatment of the support before the zeolite synthesis improves the separation performance.