A radial flow steam turbine, with combined impulse and reaction stages on the one rotor. Each set of blades of the turbine has multiple impulse stages with the steam flowing radially inward towards the rotor axis, and leading to multiple reaction stages with the steam flowing radially outward and away from the rotor axis. The impulse stage passages have a tapered shape to accommodate the increase in the volume of steam through the concentric stages of blades with the blades being progressively larger in each circular stage. The reaction passage is of uniform cross-sectional area as the increase in velocity of steam compensates for the increase in steam volume through the passage.