A pressure gas engine in which pressurized gas such as air is supplied to a series of arcuately arranged nozzles for blasting the gas into a single series of closely adjacent impulse buckets in a rotor at its rim. Each bucket lies on a chord of the rim that is adjacent to a tangent to the rim that is parallel to this chord. Each bucket has an arcuate impulse surface of substantially constant radius transverse to the direction of rotation of the rotor and extending from an entrance side of the bucket that is adjacent to one end of the bucket to an opposite exhaust side adjacent to the opposite end of the bucket with each exhaust being subjected to minimum back pressure for maximum efficiency. There is also provided nozzle means comprising an arcuate series of nozzles in the casing around the rotor and closely adjacent to the rim for providing these gas blasts through the nozzles into the buckets for rotating the rotor.