TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Apparatus: In the apparatus, the form of a heat exchange reformer is selected from bayonet tube type reactor, tube and shell heat exchanger, a double-tube reactor with catalyst disposed inside the double tubes, a double-tube reactor with catalyst disposed outside the double tubes, and a double-tube reactor with catalyst disposed inside and outside the double tubes. The heat exchange reformer is a double-tube reactor with catalyst disposed inside the double tubes, where the cooling medium (13) enters each catalyst tube (102) through tube apertures (102b) provided along the length of the upper portion (102a) of the catalyst tubes (102) and mixes with the hydrocarbon feedstock (11) entering at the top of the catalyst tubes (102), and where means 102c extends along this upper portion (102a) of the catalyst tubes (102) and create a space 102d along the length of the catalyst tubes (102) for the passage of the cooling medium 13. Heat exchange reformer is a shell and tube heat exchanger with baffles (105a) where catalyst is disposed inside the tubes (102), where the cooling medium (13) enters each catalyst tube (102) through tube apertures (102b) provided along the length of the upper portion (102a) of the catalyst tubes (102) and mixes with the hydrocarbon feedstock (11) entering at the top of the catalyst tubes (102), and where means 102c extend along this upper portion (102a) of the catalyst tubes (102) and create a space 102d along the length of the catalyst tubes (102) for the passage of the cooling medium 13. Preferred Process: Production of synthesis gas from hydrocarbon feedstock in the apparatus further comprises adding the cooling medium directly to the tube supporting structure of the heat exchange reformer; and mixing the cooling medium in the heat exchange reformer with the hydrocarbon feedstock entering the heat exchange reformer. The cooling medium is steam. It makes contact with the hydrocarbon feedstock outside the catalyst tubes. It makes contact with the hydrocarbon-mixture inside the catalyst tubes. The process also comprises passing the synthesis gas from the heat exchange reformer through an autothermal reforming stage (ATR) provided with a fixed bed of catalyst, or partial oxidation stage (POx), withdrawing a hot effluent stream of synthesis gas of which at least a portion is used as the heating medium in the heat exchange reformer, and withdrawing from the heat exchange reformer a final stream of cooled synthesis gas; and converting the effluent of synthesis gas of step (b) into ammonia synthesis gas, methanol synthesis gas, dimethyl ether (DME) synthesis gas, synthesis gas for production of hydrocarbons by Fischer-Tropsch synthesis, or hydrogen.