A single-disc high-consistency refiner for refining lignocellulosic material for paper and board manufacturing, comprising a stationary refining element and an opposed rotatable refining element, the stationary and rotatable refining elements each comprising at least one radially inner blade element (4, 14) having blade bars and blade grooves providing an inner refining surface area (7, 17) of the refining element (2, 12) and at least one radially outer blade element (8, 18) having blade bars and blade grooves providing an outer refining surface area (11, 21) of the refining element (2, 12), the inner refining surface area (7, 17) and the outer refining surface area (11, 21) of each refining element (2, 12) together providing a refining surface of the refining element (2, 12), and that there is a blade gap between the opposite refining elements (2, 12) having a height defined as a distance between bottoms of blade grooves (6, 10, 16, 20) of the opposite refining elements (2, 12) on the same radial level, characterized in that the outer refining surface areas (11, 21) of the refining elements (2, 12) comprise, in a radial direction of the refining elements (2, 12), a feed zone followed by a treatment zone, the feed zone being intended to supply the material to be refined towards the treatment zone comprising at least a defibration zone, and that a transition point where the feed zone ends and the treatment zone begins is located at a radial distance of 70 - 90% from the centre of the refiner or at a radial distance of 50 - 80% from the innermost edge (25, 27) of the refining element (2, 12) or at a radial distance of 20 - 50% from the inner edge of the outer blade element (8, 18, 33) towards the outermost edge (26, 28) of the refining element (2, 12), and that the feed zone of the outer refining surface area of the rotatable refining element comprises at least one feed bar extending towards the treatment zone for feeding lignocellulosic material to be fed to the refiner towards the treatment zones of the refining elements (2, 12) of the refiner, and that the feed bar at the feed zone is arranged to extend towards the stationary refining element over an imaginary centre line halving the blade gap in the height direction of the blade gap, and that the height of the feed bar at the feed zone is arranged to decrease towards the outer circumference of the rotatable refining element, and that the maximum height of the feed bar at the feed zone of the rotatable refining element is 50 - 95%, preferably 60 - 95%, or more preferably 70 - 90%, of the height of the blade gap. the outer refining surface areas (11, 21) of the refining elements (2, 12) comprise, in a radial direction of the refining elements (2, 12), a feed zone followed by a treatment zone, the feed zone being intended to supply the material to be refined towards the treatment zone comprising at least a defibration zone, and that a transition point where the feed zone ends and the treatment zone begins is located at a radial distance of 70 - 90% from the centre of the refiner or at a radial distance of 50 - 80% from the innermost edge (25, 27) of the refining element (2, 12) or at a radial distance of 20 - 50% from the inner edge of the outer blade element (8, 18, 33) towards the outermost edge (26, 28) of the refining element (2, 12), and that the feed zone of the outer refining surface area of the rotatable refining element comprises at least one feed bar extending towards the treatment zone for feeding lignocellulosic material to be fed to the refiner towards the treatment zones of the refining elements (2, 12) of the refiner, and that the feed bar at the feed zone is arranged to extend towards the stationary refining element over an imaginary centre line halving the blade gap in the height direction of the blade gap, and that the height of the feed bar at the feed zone is arranged to decrease towards the outer circumference of the rotatable refining element, and that the maximum height of the feed bar at the feed zone of the rotatable refining element is 50 - 95%, preferably 60 - 95%, or more preferably 70 - 90%, of the height of the blade gap.