Latest developments in proton conductors Ann. Chim. Sci. Mat, 1999,24, pp.1-18 LATEST DEVELOPMENTS IN PROTON CONDUCTORS Ph. COLOMBAN Laboratoire de Dynamique, Interactions et Reactivite, CNRS UPR1580, 2 rue Henri Dunant, 94320 Thiais, France. Abstract - Solid proton conductors are receiving considerable attention, stimulated by the need of pollution control and with the objective to develop future microprotonics. The latest striking developments in the study of proton conductors are presented : i) Hydrogen containing perovskites, with a discussion of the nature and location of hydrogen in protonic and electronic high-temperature superconductors ; ii) Novel forms of hydrogen in disordered and mixed conductors, with the problems of the vibrational proton transfer assistance assumed by some authors and the independent proton dynamics evidenced by inelastic neutron scattering; iii) Frequency dependent conductivity and dielectric relaxation, including thermally stimulated current experiments in hydrated synthetic and biological gels (seeds); iv) Proton conducting membranes as candidates to replace Nafionf-like materials in H 2 (methanol) fuel cells. Resume - Etudes reeentes sur les conducteurs protoniques. La recherche d'energies moins polluantes et la possibilite d'une microprotonique font des conducteurs protoniques des materiaux tres etudies, Les developpements les plus marquants sont analyses dans le memoire, Ii savoir la nature et les sites de l'hydrogene dans les structures perovskites hydrogenees, superconducteurs elecrronique ou protonique, les formes nouvelles de I'hydrogene dans les conducteurs mixtes, desordonnes et le debat entre un eventuel mecanisme de transfert assiste et une independence vibrationnelle des hydrogenes, la conductivite et plus generalement toutes les methodes electriques dependant de la frequence (relaxation dielectrique, courants thermostimules). Entin, Ie point est fait sur la recherche de membranes Ii conduction protonique susceptible de remplacer Ie Nafion" dans les piles Ii combustible. l. INlRODUCTlON Among the areas of solid-state materials science and technology which are changing very rapidly and offer the geatest promise for outstanding improvements, proton conductors seem Reprints: Ph. COLOMBAN, LADIR, CNRS, 2 rue Henri Dunant, 94320 Thiais, France.