A fuel cell is an electrochemical cell which can continuously change the chemical energy of a fuel and oxidant to electrical energy by a process involving an essentially invariant electrode-electrolyte system" (i). For good reason, this definition is placed ahead of this review of the past 25 years of "Fuel Cell History" because this time period covers the third cycle in periodic attempts to realize what W. Ostwald (2) envisioned in 1894 as an electrochemical element more efficient than the heat engine which, being based on r a n d o m energy, is limited by Carnot's law. The practical experiment of W. R. Grove (3) (usually called the first electrolysis fuel cell discovery) was, in its time, just a laboratory curiosity. However, around the turn of the century such eminent physicochemists as Nernst and Haber devoted much effort to direct carbon-oxidizing fuel cells. Their expectations failed due mainly to operating difficulties and m a t erial problems; that ended the first period. After World War I, new activities started the second cycle, still aimed at direct coal-oxidizing cells. The final statement by E. Baur (4) in his 1933 s u m m a r y paper gave the best chance for success to the galvanic element Which operated at room t e m p e r a t u r e in alkaline electrolyte with h y d r o g e n as the fuel. After 1933 followed the "quiet years" before the start of the third cycle Which was to progress on an international, worldwide basis.Bischoff, Justi, and Spengler (1956) were probably the last ones to consider a direct coal-burning fuel cell (with Cu/CuO air cathodes). The findings of the Russian O. K. Davtyan (5) published in 1946 can be considered the start of a new period of development. Davtyan's w o r k and the "Nernst mass" [a solid electrolyte based on ZrO2 (85%) and Y203 (15%)] were the starting points for G. H. Broers, working for the Dutch organization T.N.O., together with J. A. A. K e t e l a a r in the early 1950's laying the g r o u n d w o r k for successful high t e m p e r a t u r e molten carbonate cells operating on H2 and CO (6). Broers supplied the gases through porous layers and thus established a steady interface between the electrode structure and an electrolyte-containing solid m a t r i x (of MgO).Figure 1 shows the construction of this high temp e r a t u r e cell. Early w o r k on high t e m p e r a t u r e cells paralleling the efforts at T.N.O. was also done at the Sondes Place Research Institute in England by H. H. Chambers and A. D. S. T a n t r a m (7). F. T. Bacon (8) worked on high pressure h y d r o g e n -o x y g e n fuel cells at Marshall's Flying School, Limited, in Cambridge, England, for 10 years until he was successful with porous nickel gas-diffusion electrodes containing a dual-porosity structure which served to keep the reaction zone gas/liquid/solid stable through gas pressure action and balancing capillary forces.F i g u r e 2 shows a photograph of Bacon's dual-porosity electrode. His fuel cell was later to become the