NOVELTY - Removing contaminants from a carbon dioxide (CO2) rich gas stream, comprises: generating a CO2 rich gas stream that contains CO2 and a minor amount of flammable contaminants e.g. methane; introducing substantially pure oxygen into the CO2 rich gas stream to produce a combined oxygen (O2)/CO2 rich gas stream; injecting the combined O2/CO2 rich gas stream into a catalytic oxidizer reactor to produce a hot purified CO2 rich gas stream; withdrawing the hot purified CO2 rich gas stream; and using the hot purified CO2 rich gas stream for e.g. raise steam, and superheat steam.    USE - The process is useful for removing contaminants from a carbon dioxide rich gas stream.    ADVANTAGE - The process is flexible and of low cost.    DETAILED DESCRIPTION - Removing contaminants from a carbon dioxide (CO2) rich gas stream produced in a hydrogen plant, comprises: (a) generating a CO2 rich gas stream (1) that contains CO2 and a minor amount of flammable contaminants comprising hydrogen, carbon monoxide or methane (3); (b) introducing substantially pure oxygen (2) into the CO2 rich gas stream to produce a combined oxygen (O2)/CO2 rich gas stream; (c) injecting the combined O2/CO2 rich gas stream into a catalytic oxidizer reactor (5) having one or more beds of a catalyst that is selective for combusting the flammable contaminants contained in the combined O2/CO2 rich gas stream in order to combust the contaminants contained in the combined O2/CO2 rich gas stream and produce a hot purified CO2 rich gas stream, where the O2/CO2 rich gas stream is injected into the catalytic oxidizer reactor at a temperature that is sufficient to allow for the combustion of the contaminants in the CO2 rich gas stream; (d) withdrawing the hot purified CO2 rich gas stream; and (e) using the hot purified CO2 rich gas stream to raise steam, superheat steam, reform hydrocarbons, preheat natural gas and steam mixtures used as feedstock for hydrogen production, preheat combustion air for the hydrogen generator or provide heat for the regeneration of CO2 sorbent beds.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a process for removing contaminants from a carbon dioxide rich gas stream.    Carbon dioxide stream (1)    Oxygen source (2)    Methane (3)    Catalytic oxidizer reactor (5)    Heat exchanger. (9a, 9b, 9c)