Abstract: The invention relates to an exhaust gas purifier and a catalytic method of purifying exhaust gas, in which exhaust gas led into a combustion chamber (5) of the exhaust gas purifier, the exhaust gas is brought to centrifugal rotational motion, by which the exhaust gas flow is divided into a particle flow (9) and an actual gas flow (10). The particle flow (9) separated from the actual gas flow is retarded in relation to the actual gas flow (10). The direction of propagation of the particle flow is turned to be essentially opposite and the particle flow is rejoined to the actual gas flow and the rejoined exhaust gas flow is directed through a catalyst element (6).