Abstract: The reformer is designed for use with a large fuel cell power plant capable of producing megawatts of power, as, for example, would be used by a public utility. The catalyst tubes in the reformer have their upper ends at staggered elevations so as to be capable of having their temperatures individually monitored by infrared temperature sensors. The catalyst tubes are mounted on a floating support within the reformer housing so as to be free to undergo expansion and contraction during periods of internal temperature variation as the reformer is operated. The floating support is preferably formed from fuel manifolds suspended in the reformer housing. Baffles are included in the reformer housing for evenly distributing heat to the catalyst tube arrays. The reformer has a long burner tube which is approximately the same length as the catalyst tubes.