The original and desalination tested MFI-type silicalite membrane was characterised by XRD, SEM/EDS and single gas (He or N2) permeation to determine any changes in membrane structure, morphology and surface elements after a long term desalination testing at different temperatures. Prior to characterisation, the desalination tested membrane underwent deionised water permeation to remove weakly adsorbed material (including ions). The structure of the membrane was determined by XRD (D8-Advance, Bruker) and the XRD patterns showed no significant differences before and after long term seawater desalination testing. The textures of the membrane were observed by FESEM (S-4800, Hitachi) and the element analysis of the samples was carried out by EDS