CNES's involvement in research work into space cryogenics began at a very early stage.METEOSAT's passive cryogenic radiator was designed by CNES around 1970. Work on mechanical cryogenic machines began around 1985 with theoretical studies. The first basic mock-ups were made in 1990 for Vuilleumier and Stirling cycle machines. This work led to the completion in 1993 of two breadboards (CEA/CENG and L'AIR LIQUIDE).During this time, CNES developed a space experiment for the OMEGA project using a Stirling machine in the tactical class which was subject to a qualification cycle specially designed for the project.In order to promote very low-temperature astronomy experiments, CNES began the space qualification of a cooler developed by the CNRS/CRTBT in Grenoble. This system uses the dilution of helium 3 in helium 4 to lower temperatures from 4 K to 0.1 K. A temperature of 4 K can be obtained either with a helium bath or a mechanical cryogenic machine.Pulse tubes are a promising system for the future as they have no moving mechanical parts, no friction and no vibrations. In the near future, such tubes could replace the Stirling cycle space machine displacers. CNES is interested in the development of such systems and several French laboratories and manufacturers are at the forefront of research in this area.For the IASI project, a passive cryogenic radiator for a sun-synchronous orbit is being designed by AEROSPATIALE at Cannes. It will reach 100 K with a cooling capacity of 400 mW.CNES is also participating in the design and development of numerous other space experiments using cryogenic techniques and is conducting a research plan on cryocoolers.