Abstract: A process is provided for manufacturing groundwood pulp of uniform quality by maintaining a high and uniform moisture content in the wood in the grinding zone which comprises grinding debarked wood logs or wood chips in a closed pocket grinder under atmospheric or superatmospheric pressure while applying shower water both to the free surfaces of the grindstone and to the grinding zone where the logs or chips are in contact with the grindstone, such as by spraying the water at the end portions of the logs or chip mass, optionally together with applying shower water via the ram plates and a water trap arranged around the lower part of the log pockets, and preferably retaining shower water within the grinding zone by filling with shower water the hollows between the logs or chips located nearest the surface of the grindstone.