The shipping industry is becoming increasingly visible on the global environmental agenda. Shipping's share of air pollution is becoming significant, and public concern has led to ongoing political pressure to reduce shipping emissions. International legislation at the IMO governing the reduction of SOx and NOx emissions from shipping is being enforced, and both the European Union and the USA are planning to introduce further regional laws to reduce emissions. Therefore, new approaches for more environmental friendly and energy efficient energy converter are under discussion. One possible solution will be the use of fuel cell systems for auxiliary power or even main propulsion. The paper summarizes the legal background in international shipping related to the use of fuel cells and gas as fuelin ships. The focus of the paper will be on the first experiences on the use of fuel cell systems on board of ships. In this respect an incident on a fuel cell ship in Hamburg will be discussed. Moreover, the paper will point out the potential for the use of fuel cell systems on board. Finally, an outlook is given on ongoing and planed projects for the use of fuel cells on board of ships.