(EP896741-A1)      Preparing a cation exchange membrane comprises incorporating an organic polymer (A) with sulphonic acid groups and finely distributed electrically conductive catalyst material particles (B) into an aqueous phase and then coating at least one side of a cation exchange material (C) film with the resulting suspension.(A) is soluble in an aprotic polar solvent and contains repeat units of formula (Ar1X) (I) or (Ar2Y) (II) at least partially substituted with sulphonic acid groups. In the formulae: Ar1 and Ar2 = arylene; X = O or S; and Y = carbonyl, sulphoxide or sulphonyl. A suspension is formed by adding (B) to a solution of (A) in a solvent. (C) contains a cation exchange resin with sulphonic acid groups. The coating on the film is treated with a liquid which is miscible with the solvent for (A) but is not capable of dissolving (A), resulting in coagulation to form pores in the membrane coating.    USE -   The membranes are used as proton conductor membranes in electrochemical fuel cells. They can also be used in electrolysis cells or membrane fuel cells.    ADVANTAGE -   The catalytic cation exchange materials show improved resistance to chlorine and alkalis, are relatively cheap and can be processed more easily due to their good solubility.    (EP896741-B1)      Preparing a cation exchange membrane comprises incorporating an organic polymer (A) with sulphonic acid groups and finely distributed electrically conductive catalyst material particles (B) into an aqueous phase and then coating at least one side of a cation exchange material (C) film with the resulting suspension.(A) is soluble in an aprotic polar solvent and contains repeat units of formula (Ar1X) (I) or (Ar2Y) (II) at least partially substituted with sulphonic acid groups. In the formulae: Ar1 and Ar2 = arylene; X = O or S; and Y = carbonyl, sulphoxide or sulphonyl. A suspension is formed by adding (B) to a solution of (A) in a solvent. (C) contains a cation exchange resin with sulphonic acid groups. The coating on the film is treated with a liquid which is miscible with the solvent for (A) but is not capable of dissolving (A), resulting in coagulation to form pores in the membrane coating.    USE -   The membranes are used as proton conductor membranes in electrochemical fuel cells. They can also be used in electrolysis cells or membrane fuel cells.    ADVANTAGE -   The catalytic cation exchange materials show improved resistance to chlorine and alkalis, are relatively cheap and can be processed more easily due to their good solubility.    (JP2000509187-W)      Preparing a cation exchange membrane comprises incorporating an organic polymer (A) with sulphonic acid groups and finely distributed electrically conductive catalyst material particles (B) into an aqueous phase and then coating at least one side of a cation exchange material (C) film with the resulting suspension.(A) is soluble in an aprotic polar solvent and contains repeat units of formula (Ar1X) (I) or (Ar2Y) (II) at least partially substituted with sulphonic acid groups. In the formulae: Ar1 and Ar2 = arylene; X = O or S; and Y = carbonyl, sulphoxide or sulphonyl. A suspension is formed by adding (B) to a solution of (A) in a solvent. (C) contains a cation exchange resin with sulphonic acid groups. The coating on the film is treated with a liquid which is miscible with the solvent for (A) but is not capable of dissolving (A), resulting in coagulation to form pores in the membrane coating.    USE -   The membranes are used as proton conductor membranes in electrochemical fuel cells. They can also be used in electrolysis cells or membrane fuel cells.    ADVANTAGE -   The catalytic cation exchange materials show improved resistance to chlorine and alkalis, are relatively cheap and can be processed more easily due to their good solubility.    (US6214891-B1)      Preparing a cation exchange membrane comprises incorporating an organic polymer (A) with sulphonic acid groups and finely distributed electrically conductive catalyst material particles (B) into an aqueous phase and then coating at least one side of a cation exchange material (C) film with the resulting suspension.(A) is soluble in an aprotic polar solvent and contains repeat units of formula (Ar1X) (I) or (Ar2Y) (II) at least partially substituted with sulphonic acid groups. In the formulae: Ar1 and Ar2 = arylene; X = O or S; and Y = carbonyl, sulphoxide or sulphonyl. A suspension is formed by adding (B) to a solution of (A) in a solvent. (C) contains a cation exchange resin with sulphonic acid groups. The coating on the film is treated with a liquid which is miscible with the solvent for (A) but is not capable of dissolving (A), resulting in coagulation to form pores in the membrane coating.    USE -   The membranes are used as proton conductor membranes in electrochemical fuel cells. They can also be used in electrolysis cells or membrane fuel cells.    ADVANTAGE -   The catalytic cation exchange materials show improved resistance to chlorine and alkalis, are relatively cheap and can be processed more easily due to their good solubility.