Abstract: A method for the fabrication of an electrochemical cell which has long term chemical stability to anolyte and catholyte solutions at pH's of less than 2 and above 12, which method comprises the steps of: i) thermally processing a polymeric material which exhibits a glass transition to form the cell structure or components of the cell structure, and ii) subjecting the surfaces of the cell structure of components of the cell structure, which in use, will be in contact with the anolyte and catholyte solutions, to a post halogenation process, whereby the polymeric material forming the said surfaces undergoes halogen substitution to form a chemically stable halogen modified polymeric material.