In a diffusor for an axial-flow steam turbine with an axial/radial diffusor, the kink angles of the diffusor inlet both at the hub and at the cylinder of the turbo-machine are determined solely for the purpose of equalizing the total pressure profile over the channel height at the outlet of the last blade row. The diffusor is subdivided from the inlet to the outlet into an inner and an outer channel by a radially outward-curved guide plate. Within the deceleration zone of the diffusor, radial-flow flow ribs are arranged in the outer channel and diagonal-flow flow ribs are arranged in the inner channel for canceling the rotation of the rotational flow.