Introduction At the bore well natural gas is saturated with water. Downstream the presence of water may cause: formation of methane hydrates (blocking eventually the pipeline), condensation of water in the pipeline and corrosion effects. A process used for the dehydration of natural gas is glycol absorption. This process has several disadvantages like glycol regeneration, loss of glycol due to contamination with aromatic hydrocarbons, large and heavy equipment (especially offshore) and maintenance. Membrane processes do not have these disadvantages and are therefore a viable alternative. The aim of this project is to study membrane materials and their transport characteristics for the dehydration of natural gas at temperatures up to 80°C and pressures up to 80 bars. In this presentation the water vapor and gas transport properties through PEO PBT blockcopolymers are discussed.