A method of treating a gaseous mixture comprising hydrogen and carbon dioxide separates the hydrogen (H2) gas and crude carbon dioxide (CO2) gas from the gaseous mixture thereof. Combustible gas(es) in the crude CO2 gas are combusted to produce heat, at least a portion of which is recovered by indirect heat exchange with at least a portion of the separated H2 gas or a gas derived therefrom. The invention may be integrated with coal-fired power stations to reduce or eliminate emission of harmful components into the atmosphere.