The invention relates to a method and an apparatus for removing impurities from a gasification gas, wherein the gasification gas which includes at least tars and/or undesired hydrocarbons is supplied to a catalytic reformer which has at least one catalyst bed, oxygen containing gas is injected onto the surface of the catalyst bed, the gasification gas is arranged to flow through the catalyst bed and arranged to contact with the oxygen containing gas in the catalyst bed, and a purified gas is discharged from the catalytic reformer. Further, the invention relates to the use of the method.