Аннотация:The project of a spectrometer of hard X (X-h)-rays and gamma-rays (approximate energy range 0.05 - 50 MeV) was proposed to a competition of scientific instruments to be accommodated onboard the international space station (ISS). The objectives of this experiment are as follows: detailed study of astrophysical phenomena including cosmic gamma-ray bursts (GRB), lines in Galactic diffuse background, e(+)e(-) annihilation line from the Galactic Centre and high resolution observation of solar X-h-rays and gamma-radiation in lines and continuum. The spectrometer detector system includes three enriched Ge crystals (each of similar to 200 cm(3) volume) cooled to <100K and six NaI/CsI phoswich detectors (each of similar to 10(4) cm(3) volume) with crossed axes. The effective instrument field of view is about pi sr. The expected energy resolution at 1 MeV for Ge and NaI are similar to 2 keV and similar to 50 keV, respectively. The detection of solar flares neutrons is also possible by this instrument owing to the separation of different components of light flashes in CsI. The program of ISS provides a long exposure time for the detectors of the proposed spectrometer. Using results of the "Grif-1" experiment onboard the "Mir" station we obtain that it will be possible to accomplish precise Xh and gamma-measurements under background conditions onboard ISS. (C) 2000 COSPAR. Published by Elsevier Science Ltd.