The subject invention refers to a muffler comprising a muffler housing (1, 2) and generally a catalytic converter element (13) mounted in the housing, which muffler has at least one inner outlet (4) through which exhaust gases cleaned by the catalytic element (13) are intended to pass. Furthermore, according to the invention an outlet duct (30, 31) is arranged in connection to the outside of the housing, comprising a first section (30) for leading exhaust gases in a first direction (A) in parallel with the outside of the housing, and a second section (31) for leading exhaust gases in a second, opposite direction (B), whereby said first and second sections (30, 31) have an essentially equally large cross-sectional area. By way of this outlet duct an improved cooling of the exhaust gases before they are brought in contact with fresh air rich in oxygen can be achieved. A back-pulsation of fresh air into the muffler can also be prevented.