Fuel cell generators are reviewed from the viewpoint of systems, markets, emissions, and cost-reduction. Their most attractive features are likely to be their unobtrusiveness, which includes very low emissions, combined with their availability in small sizes, allowing cogeneration at the widest range of sites. Unattended operation and very high availability will result in low O&M costs. System designs require rethinking with a view to cost reduction, to make them more attractive compared with competing technologies. This is being pursued by developers. The fuel cell promises to be an important energy conversion technology, which will help to reduce carbon dioxide emissions in the next century. This review covers progress in the phosphoric acid fuel cell (PAFC), molten carbonate fuel cell (MCFC) and solid oxide fuel cell (SOFC) technologies for stationary applications. Although not exhaustive, it attempts to review the literature in a general manner from 1989, when the last overview (Ref. 6) was published. It more extensively reviews papers and presentations at symposia and conferences from 1991 to May 1995. A general review of engineering activity to August 1995 is included.