A device for determining the microstructure of a metal product during metallurgical production of the metal product, the device having at least one X-ray source, at least one X-ray detector and at least one accommodating chamber, inside which the X-ray source and/or the X-ray detector is/are arranged and which has at least one window which is transparent to X-ray radiation. To allow reliable determination of the microstructure of a metal product during the metallurgical production thereof, the device includes at least one cooling installation for actively cooling the accommodating chamber.