Properties of the room-temperature liquid complex salt [Ag (propene) x][Tf2N] have been studied to probe its suitability for acting as active separation layer in immobilised liquid membrane (ILM) concepts for propane/propene separation. The pressure/temperature range of complex formation has been determined and the thermal properties of Ag [Tf2N] and [Ag (propene) x][Tf2N] have been studied by DSC (differential scanning calorimetry) and TGA ...