[en] For certain classes of neutron scattering experiments it is desirable to increase the neutron intensity at energies above the Maxwellian peak of a reactor spectrum considerably. This can be done by installing a piece of moderator having a high temperature, a so-called hot source, at the tip of the beam tube. In our experiments we used graphite as material for the hot source. The possible gain in neutron intensity attainable with a hot source was studied in a mock-up experiment for various sizes and temperatures of the graphite block using the pulsed neutron technique. The agreement of the measurements with calculations of the rethermalization properties of the graphite block based on transport theory was quite satisfactory. A plug carrying a graphite cylinder, 18 cm in diameter and 18 cm in height, was installed at the FR2 reactor. With proper thermal isolation a graphite temperature of about 1700°K was reached by nuclear heating only. Spectrum measurements at this temperature and systematic studies of the properties of the hot source are under way. An increase in neutron intensity of about a factor of 7 is expected at a neutron energy of 0.3 eV. The source will be first used for phonon dispersion measurements. (author)