Abstract: A catalytic reformer assembly and methods of operation, including fast start-up. The reformer assembly includes a reactor for receiving hydrocarbon fuel and air and a reforming catalyst within the reactor for converting the fuel and air to hydrogen-containing reformate. The assembly further includes a heat exchanger that straddles the reformer such that gases entering and leaving the reformer pass through opposite sides of the heat exchanger. A combustor ahead of the heat exchanger includes a first fuel injector and igniter. A fuel/air mixture may be either ignited at start-up to quickly heat both sides of the heat exchanger, the reactor, and the reformer, or passed into the reactor for reforming at steady state. A second fuel injector may be provided in the reactor. The two fuel injectors may have overlapping flow ranges and may be used separately or in tandem to provide a broad range of reformate flow.