A method of and an apparatus for capturing CO2 from flue gas emanating from a carbonaceous fuel combusting power plant, which includes a source of oxygen and a combustion chamber for combusting the fuel with oxygen and thereby producing flue gas that includes CO2, water and excess oxygen as its main components. At least a portion of the flue gas is compressed to a pressure higher than about sixty bar, the compressed flue gas is cooled in a primary CO2 separating unit for capturing a first portion of the CO2 by condensing it to produce a liquid CO2 stream and a high pressure vent gas stream that includes oxygen and excess CO2, the liquid CO2 stream is discharged from the power plant, and the high pressure vent gas stream is conducted to a secondary CO2 separating unit for capturing a second portion of the CO2 by adsorbing it to an adsorbing material.