A method and device for separating at least one catalyst from a mixture of homogeneously shaped catalysts, the catalysts comprising at least one metal selected from the group formed by Ni, Co, Mo, W, the catalyst to be separated comprising a characteristic metal selected from the group formed by Ni, Co, Mo, W and the other catalysts of the mixture not containing said characteristic metal, in which method: the grains of the catalyst of said mixture pass in front of the LIBS detection system, the presence of said characteristic metal in the catalysts is detected by the LIBS technique, the wavelength being selected so as to detect said characteristic metal, the LIBS detection system sends a signal to a means for evacuating grains of catalyst to be separated in a manner such as to separate said grains from the other catalysts of said mixture.