NOVELTY - A proton conductive polymer/ceramic particle composite or composite membrane, consisting of a polymer and oxide nanoparticles with intercalated water and high surface hydroxyl concentration, is new.    USE - In fuel cells (direct methanol, H2 and hydrocarbon fuel cells), batteries (especially secondary batteries), hot gas methane reforming for methanol or ethanol synthesis, hydrogen production from steam, electrochemical sensors e.g. for H2, CHx and NOx, medicine and electrocatalysis (claimed), as well as in gas sensors and hydrogen pumps in nuclear technology.    ADVANTAGE - The composite is suitable for use in medium to high temperature (above 100 degreesC) fuel cells and has satisfactory proton conductivity at up to 300 degreesC. Additionally, the composite exhibits H2O storage capability at up to 250-300 degreesC at atmospheric pressure (up to 500 degreesC at elevated pressure), H+ conduction via a water and hydroxyl containing interface structure at up to at least250 degreesC, targeted variation of local charge carrier binding strengths at various polar groups of the polymer framework and at the ceramic particle surfaces, easy deformability to produce shaped bodies and low water management servicing and regulation requirements during use at above 100 degreesC.    DETAILED DESCRIPTION - A novel proton conductive polymer/ceramic particle composite or composite membrane consists of a temperature resistant polymer and oxide nanoparticles (much greater than 20 m2/g surface and much less than 100 nm mean diameter) with intercalated water and a high concentration of acidic/basic surface OH. INDEPENDENT CLAIMS are also included for the following:    (i) a hydroxyl ion conductive polymer/ceramic particle composite as described above, in which the polymer can contain anion exchange groups of NR4 (R = H, alkyl, aryl), pyridinium, imidazolium, pyrazolium, sulfonium; and    (ii) production of the above hydroxyl ion or proton conductive polymer/ceramic particle composite by dispersing the polymer and the nanoparticles in a solvent and then evaporating off the solvent.