This contribution presents a study about the design and the manufacturing of a fluidized bed furnace. Nitriding was carried out by using fluidized bed furnace and optimum process parameters were determined for nitriding. In these experiments DIN 7225 and DIN 8550 steels were used, and as a first step two types of steel were hardened and tempered. Nitriding was carried out by using N-2 + NH3 at 520 degrees C and 570 degrees C. Nitriding times were selected as 3, 6 and 12 hours. The thickness of nitride layers varied from 6.1 to 39.73 mm. The hardness of nitride layers varied from 605 to 1114 MPa. The tensile strength of the specimens were found between 618 and 1162 MPa. Their yield strength values varied from 479 to 939 MPa and their impact resistance values were found between 2.25 J/cm(2) and 84 J/cm(2). Effect of nitriding on the mechanical properties of the specimens are discussed.