TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: In the method, the hydrocarbon feed is natural gas or a gas stream containing greater than 90 vol.% methane or naphtha; the purification sorbents include a sulfur sorbent and/or a chloride sorbent; the steam is combined with the purified hydrocarbon by means of a saturator or by direct injection such that the steam ratio of 1.8-2.5; the pre-reforming catalyst comprises Ni at greater than 40 wt.%; the pre-reformed gas mixture is split and a first portion fed to the fired steam reformer and a second portion sent to a gas heated reformer, where the gas-heated reformer is heated by the crude synthesis gas collected from the tubes of the fired reformer and the product crude synthesis gas is recovered both from the tubes and shell side of the gas heated reformer; the percentage volume of pre-reformed gas fed to the gas-heated reformer is 10-90 (preferably less than or equal to 50, especially less than or equal to 40) vol.%; the reforming catalyst used in the tubes of the steam reformer comprises nickel (10-30 wt.%) supported on a refractory support and preferably alkali-promoted, and optionally containing a precious metal; the shift stage comprises a high temperature shift stage over an iron catalyst with an inlet temperature of 310-360 degrees C and a low temperature shift stage at an inlet temperature of 200-220 degrees C over a copper catalyst, or a medium temperature shift stage at an inlet temperature of 240-280 degrees C over a stabilized copper catalyst; the medium temperature shift stage is operated isothermally; the shifted gas mixture is cooled to at a temperature less than or equal to 160 degrees C and the carbon dioxide-selective membrane reactor comprises a polymer membrane with the following characteristic selected from temperature limit of 165 degrees C, a pressure limit of 10 bara, a carbon dioxide permeance of 8x 10-5 to 1x 10-4 mol/m2 s kPa, and a carbon dioxide/hydrogen selectivity of 120-160; the water-gas shift catalyst in the carbon dioxide-selective membrane shift reactor is a copper catalyst or a precious metal catalyst or its mixture; the selective membrane shift reactor contains cooling unit to prevent the temperature rise associated with the exothermic water-gas shift reaction damaging the carbon dioxide-selective membrane; the selective membrane shift reactor is provided with low-pressure steam as a sweeping gas; the purge gas stream is recycled to the hydrocarbon feed or purified hydrocarbon feed streams; and the purge stream is divided and at least a portion supplied to at least two of the fuel to the fired steam reformer, the hydrocarbon feed and the purified hydrocarbon feed. EXAMPLE - No suitable example given.