Abstract: Method and an apparatus for controlling the production of thermomechanical pulp meter chips by metering elements (9, 10) into a feed chest (2), and by feed elements (3, 7) connected to the feed chest feeds chips for refinement between thermomechanical pulp refining discs (5). Water is added to the chips prior to feeding the chips between the discs (5). Moisture content of the thermomechanical pulp is measured after the thermomechanical pulp refiner at least in a semicontinuous fashion by at least one measurement device (21, 22, 23, 24) operating on-line, and on the basis of measured moisture content, the quantity of chips and water to be metered is controlled so as to regulate the moisture content to a desired level of having a constant value by, e.g., increasing the volume of metered chips and simultaneously decreasing the quantity of fed water for an increasing trend of moisture content, and correspondingly, applying an opposite strategy to counter a decreasing trend of moisture content.