TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred System: The monitoring unit comprises unit for on-line collection of electrical data of the pelletizer motor. The comparison unit is a computer assisted device for continuously testing if the motor current is within set targeted values regarding the actual read-out of electrical data and regarding variability measurement within a successive moving window of actual and preceding observed read-outs of electrical data. The computer assisted device is adapted to generate regulation signals to regulators controlling infusion of cooling media, either to the feed layer or to the die surface or to both, or in channels or on flanges connected to the die when the actual current and/or the actual variability measurement pass set targeted values. The system further comprises a sensor for recording feed layer temperature, die surface temperature and/or die temperature. The cooling media is any of water aerosols, liquids and/or gases (e.g. air). The targets for the electrical variability measurement are set at several coefficients of variation of 0-3 (preferably 0-0.2). The preset target value for basic cooling equals the heat remaining after heating of the raw material, evaporating moisture etc, e.g. 25-80% of the mechanical work done by the motor at continuous pellet production minus that of idle running at no production at all. The system further comprises a control unit for evaluating the preset value for basic cooling at every major disturbance of the feed layer formation, e.g. after an intermittent pellet production cycle, to calculate if the preset value should be changed. The system comprises unit for controlling the feed layer temperature, die surface temperature and/or die temperature is/are to between 0-80 (preferably 0-50) degrees C. Preferred Method: The motor is an electric motor and the measurement performed is a measurement of the motor current of the pelletizer to provide motor current data. The measurements of the electric motor current are continuous in pelletizer operation and where the method further involves continuous calculations of the variability measure of the current. The method involves selecting target values for the variable from values inside an interval covering mean motor current ( mu ) at the ongoing production rate at continuous production plus/minus one standard deviation ( plus minus delta ) of the current at continuous production, i.e. psi + delta , preferably mu + kx o (where k is 1-3 (preferably an asymmetrical interval from jx (Ideal current), where j is 1 to 1.5)) and k is a value between 1 and 3). The regulator controls infusion of cooling media either to the feed layer or to the die surface or to both, or into channels in the die or onto flanges connected to the die. The method is an iterative process to set suitable target values for the electrical current and the variability measurement of that current and to set a basic cooling of the die surface using cooling media. The targets for the electrical variability measurement are set at several coefficients of variation in the range of 0-3 (preferably 0-0.2). The preset target value for basic cooling equals the heat remaining after heating of the raw material, evaporating moisture etc, e.g. 25-80% of the mechanical work done by the motor at continuous pellet production minus that of idle running at no production at all plus possible heat originating from steam addition. The method further involves evaluating the preset value for basic cooling at every major disturbance of the feed layer formation, e.g. after an intermittent pellet production cycle, to calculate if the preset value should be changed. The feed layer temperature, die surface temperature and/or die temperature is/are controlled to 0-80 (preferably 20-70) degrees C. The measurement performed is a measurement of the die temperature and/ or the die surface temperature. The measurement performed is a measurement of the feed-layer thickness. The method further involves, in a situation where cooling of the feed layer, the die surface and/or the die alone is not sufficient to cancel disturbances in the feed-layer formation, adding press helpers, such as powder or granules of lignin, starch, plastics, sugar, oils, fats, rape seed cake, and/or water. EXAMPLE - No suitable example is given.