Abstract: A steam generator for a fuel cell system having a heat exchanger (34) with at least one internal heat exchange surface, a water inflow pipe (46), a dripper head (52) with a flow passageway fluidly connected to the water inflow pipe (46). The dripper head (52) extends inside the heat exchanger (52) above the heat exchange surface for feeding water down onto the heat exchange surface for conversion into steam. The dripper head (52) has outlet holes (56) spaced along the flow passageway and between adjacent outlet (holes 56) the dripper head has a stepped profile on at least its underside to prevent droplets from adjacent holes coalescing. A fuel inflow pipe can have a section mounted coaxially to a part of the water inflow pipe (46). The fuel inflow pipe's section can surround the water inflow pipe's part.