The invention concerns a method for combined production of hydrogen and carbon dioxide from a mixture of hydrocarbons wherein the residual PSA is treated to produce a carbon dioxide-enriched fluid, and wherein: the residual PSA is compressed to a pressure such that the partial pressure of the CO₂ contained ranges between about 15 and 40 bar; the residue is subjected to one or more condensation/separation steps with production of CO₂-rich condensate(s) and a purge of noncondensable gas; the purge of noncondensable gas is preferably treated to produce a H₂-rich permeate which is recycled to the PSA, and a residue which is recycled to syngas generation, Preferably, the condensate(s) are purified by cryogenic distillation to produce food grade CO₂. The invention also concerns an installation for implementing the method.