Of the societal ills which are recognized as present in the Western countries during the 1970's, pollution of air and water is among the first. Whether the breathing of noxious gases acts biochemically as a source of mental irritation is not yet known. But it is not in doubt that reduction of the grime, smog, fouled water, and acrid air would lead to an increase in a feeling of well-being. Nor is it speculative to state that a reversal of the present trend to poison the atmosphere and the water is essential if man is to survive in a technological society. It was partly the lack of realization of the intrinsic nature of over­ potential in electrochemical reactions, * and hence the failure of the early fuel cells to come up to expectations, which led engineers at the turn of the century to rely upon the combustion of oil and coal for the production of energy, with the associated era of increasing atmospheric pollution.