NOVELTY - A proton conducting membrane comprises a dehydrogenation catalyst and at least one mixed lanthanide, tungsten, and molybdenum oxide.    USE - For dehydrogenation of alkane (claimed) to alkene.    ADVANTAGE - The material is stable in the presence of carbon dioxide and acidic gases in general making them usable in the presence of air. The tungstates form an ideal membrane that offers right hydrogen selectivity for an alkane to alkene. The membrane has better hydrogen selectivity; it ensures that the amount of hydrogen which passes through the membrane is sufficient to allow alkene (olefin/aromatic) formation but not coke formation.    DETAILED DESCRIPTION - A proton conducting membrane comprises a dehydrogenation catalyst and at least one mixed lanthanide, tungsten, and molybdenum oxide of formula LnaWb-cMocO12-y (II), where the molar ratio of a:b is 4.8-6 (preferably 5.3-6).    Ln=Y or element numbered 57-71;    c=0 to 0.5x b;and    y=number such that compound (II) is uncharged (preferably 0-1.8).    INDEPENDENT CLAIMS are included for the following:    (1) a supported proton conducting membrane comprising a porous support and a non porous proton conducting membrane on it, where the non porous proton conducting membrane comprises mixed metal oxide (II), and the support comprises a porous mixed metal oxide of formula (II);    (2) a reactor comprising a first zone containing a dehydrogenation catalyst and a second zone separated from the first zone by a proton conducting membrane having a mixed metal oxide (II);    (3) dehydrogenation of substance e.g. alkane involving introducing the substance into the first zone of a reactor to dehydrogenate the substance; allowing hydrogen formed during the dehydrogenation to pass through the proton conducting membrane into the second zone; introducing a purge gas into the second zone, preferably to react with the hydrogen; or applying reduced pressure in the second zone to thus remove hydrogen from the second zone; and    (4) formation the proton conducting membrane comprising a rare-earth tungstate (II) involving forming a solution of an organometallic compound of Ln and an organometallic compound of tungsten ions and if present molybdenum ions in an organic solvent; forming a membrane on a support by coating the support with the solution e.g. by dip coating or spray coating; drying to remove the organic solvent; and calcining to form the proton conducting membrane.