Abstract: The invention relates to combined catalytic converter and muffler device intended for attachment to the exhaust pipe of an engine, e.g. on a lawn mower. The device comprises a housing within which a catalytic substance (14) is arranged. According to the invention, the exhaust gas inlet (3) is provided with a restriction, preferably in the form of a cone (6). Thereby, an intake of a suitable amount of air is achieved through an air inlet (7), preferably comprising an air labyrinth (8). The catalytic substance (14) is preferably provided in pellet form and arranged in an annular chamber in the housing, having a circular shape. A muffling substance (16) made of glass fibre ceramics is preferably arranged in a chamber (15) outside of the catalytic substance (14).