The measurements of pollution in the troposphere (MOPITT) instrument is an IR radiometer that uses gas correlation spectroscopy to detect carbon monoxide and methane in the earth’s troposphere. The instrument concept was developed by the Department of Physics of the University of Toronto and it was designed, manufactured and tested by COM DEV Ltd., Canada, the prime contractor, for the Canadian Space Agency. MOPITT will be flown on the National Aeronautics and Space Administration (NASA) earth observing system (EOS) AM1 platform in mid 1998. The MOPITT instrument has eight optical channels that operate in the spectral band 2130 to 4510 cm-1 (2.2 to 4.6 µm). The radiometric calibration of the instrument is achieved by using four onboard compact high-emissivity calibration sources working in the range 285 to 500 K that were designed, manufactured and tested at Bomem, Inc., Canada. A description of these calibration sources and the results of the qualification and acceptance testing performed are presented.