A gas exhaust diffuser for a circuit breaker, comprising a first casing extending longitudinally along a principal axis with an open end to allow gas to enter and a closed end, and a second casing coaxial to the first casing, extending along the principal axis, with at least one outlet to allow gas to escape, the closed end of the first casing being arranged in the second casing and the first casing having at least two radial openings near its closed end to provide a fluid communication between the first and second casing. A plurality of incurved elements are positioned radially in the second casing at the at least one radial opening to create a rotation of an entering exhaust flow in a plan perpendicular to the principal axis, thereby generating a substantially helicoidally-shaped exhaust flow path in the second casing.