NOVELTY - A fuel (F1) and oxidant gas (G1) are combusted in reformer (110) to form primary combustion product gas mixture. Heated feed comprising methane and steam is reacted in adiabatic reactor (150) to form intermediate product gas mixture (103). A fuel (F2) and oxidant gas (G2) are combusted in furnace (160) to generate secondary combustion product gas mixture. Intermediate mixture is heated in furnace by indirectly transferring heat between secondary gas mixture and intermediate gas mixture. Heated mixture is reacted in reformer tubes to form a hydrogen-containing gas (105).    USE - Production of hydrogen-containing gas.    ADVANTAGE - The hydrogen-containing gas is efficiently and economically manufactured at high yield.    DETAILED DESCRIPTION - A fuel (F1) and an oxidant gas (G1) are combusted external to reformer tubes in initial section of a reformer (110) to form a primary combustion product gas mixture. The heated feed comprising methane and steam is reacted in an adiabatic reactor (150) containing a reforming catalyst under reaction conditions sufficient to form an intermediate product gas mixture (103). A fuel (F2) and oxidant gas (G2) are combusted in a furnace (160) to generate a secondary combustion product gas mixture. The intermediate product gas mixture is heated in the furnace to form a heated intermediate product gas mixture by indirectly transferring heat between the secondary combustion product gas mixture and the intermediate product gas mixture. The heated intermediate product gas mixture is reacted in reformer tubes under reaction conditions sufficient to form the hydrogen-containing gas (105). Indirect transfer of heat between the primary combustion product gas mixture and the intermediate product gas mixture is not carried out during heating of the intermediate product gas mixture. An INDEPENDENT CLAIM is included for apparatus for producing hydrogen-containing gas.    DESCRIPTION OF DRAWING(S) - The drawing shows the flow diagram explaining production of hydrogen-containing gas.    Feed (101)    Heated feed (102)    Intermediate product gas mixture (103)    Hydrogen-containing gas (105)    Reformer (110)    Adiabatic reactor (150)    Furnace (160)    Burner (167)