Abstract: The invention relates to a flow energy conversion machine having a substantially circular flow-through cross-section and comprising stationary guide blades disposed in at least one plane perpendicular to the flow direction, and rotor blades disposed in at least one plane parallel to the plane of said guide blades and cooperating with said guide blades, said guide blades being connected to a stationary part of said machine while said rotor blades are secured to a part mounted for rotation about an axis extending substantially parallel to the flow direction. In order to achieve a simple, reliable and cost-effective construction of the machine and its blades, the invention provides that the guide blades are secured to a stationary shaft located at a central position in the flow path, and that the rotor blades are secured to a rotor mounted for rotation about the centrally located shaft.