This paper describes in detail the spectral responsivity calibration of the Linear Pyrometer of the Thermal Metrology Division (Diter) of Inmetro. This calibration was performed at the Radiometry Laborator (Larad) of the Optical Metrology Division (Diopt). It was made using two different experimental setups. In the first one, mirrors were used to direct the radiation beam from the exit slit of the monochromator to the entrance of the detectors. In the second setup the detectors were aligned directly in the exit slit of the monochromator. The spectral responsivity values in the first setup were lower than the second one. The uncertainty evaluation was performed for the second configuration data. The characterisation process of the linear pyrometer, will allow the maintenance of the International Temperature Scale of 1990 (ITS-90) on the instrument itself.
