NOVELTY - Reformer unit includes a reactor vessel, a feed line for introducing an educt to the vessel; a first heat exchanger connected to the feed line consisting of a first pipe and a second pipe, a second heat exchanger connected to the first pipe and arranged around a reformer chamber.    USE - Used for producing hydrogen from an educt of a hydrocarbon-water mixture in a fuel cell.    ADVANTAGE - The unit is compact and efficient.    DETAILED DESCRIPTION - Reformer unit includes a reactor vessel (1), a feed line (2) for introducing an educt to the vessel; a first heat exchanger (3) connected to the feed line consisting of a first pipe (3a) and a second pipe (3b); a second heat exchanger (5) connected to the first pipe and arranged around a reformer chamber (6).    The reformer also includes a line (8) connected to the second heat exchanger and having an outlet opening for introducing the gaseous educt into the reformer chamber containing a catalyst unit heated by a burner (7); a removal line (9) for removing reformate formed in the reforming chamber to the second tube of the heat exchanger connected to a shift reactor (4); and a product removal line (11) for the product gas removed from the shift reactor and a removal line (12) for the waste gas from the reactor vessel.    INDEPENDENT CLAIMS are also included for: a process for producing hydrogen using the above unit; and a process for pre-heating an educt.    Preferred Features: The first heat exchanger is a coaxial heat exchanger having a first outer pipe and a second inner pipe. The product removal line is connected to a unit for cleaning the product gas, preferably for reducing the CO content in the product gas.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the reformer unit.    Reactor vessel (1)    Feed line (2)    First heat exchanger (3)    First pipe (3a)    Second pipe (3b)    Shift reactor (4)    Second heat exchanger (5)    Reformer chamber (6)    Burner (7)    Removal line (9)    Product removal line (11)    Removal line (12)