NOVELTY - Pelletizing press (3) for producing pellets (10) from a biomass (1) comprises: at least one single- or multiple-part matrix (4) with many holes for pressing the biomass; at least one roller (5) rolling on a rolling surface of the matrix; at least one driving device for the matrix and/or the roller; at least one supporting device for fixing the matrix in an operating position in the press; and at least one clamping sleeve between the matrix and the supporting device and/or within the matrix. The biomass consists of cellulose- and/or lignocellulose containing fibers, chips or particles.    USE - The pellets are useful as a fuel in fireplaces.    ADVANTAGE - The device: produces the pellets in different materials and/or geometries in the matrix; and assures shifting and twisting in an easy manner due to the combination of the matrix and the supporting device, and thus simplifies the assembly of the matrix itself and/or the assembly of the matrix in the press or on the supporting device.    DETAILED DESCRIPTION - Pelletizing press (3) for producing pellets (10) from a biomass (1) comprises: at least one single- or multiple-part matrix (4) with many holes for pressing the biomass; at least one roller (5) rolling on a rolling surface of the matrix; at least one driving device for the matrix and/or the roller; and at least one supporting device for fixing the matrix in an operating position in the pelletizing press. The biomass consists of cellulose- and/or lignocellulose containing fibers, chips or particles. At least one clamping sleeve is arranged between the matrix and the supporting device and/or within the multiple-part matrix for fixing and simultaneously balancing operational-related differences and/or manufacturing-related inaccuracies, where the clamping sleeve comprises a cylindrical tube with a longitudinal slot, and is arranged in two corresponding openings between the matrix and the supporting device and/or within the multiple-part matrix.    DESCRIPTION OF DRAWING(S) - The figures 1 and 2 show a schematic top view of the rectangular multiple-part flat matrix and an underlying supporting plate in the press with a reversing roller, and a sectional view of the matrix along a sectional line through the matrix and supporting plate.    Biomass (1)    Pelletizing press (3)    Matrix (4)    Roller (5)    Pellets (10)