The GRANAT observatory was launched into a high apogee orbit on 1 December, 1989. Three instruments onboard GRANAT - PHEBUS, WATCH and SIGMA are able to detect gamma-ray bursts in a very broad energy range from 6 keV up to 100 MeV. Over 250 gamma-ray bursts were detected. We discuss the results of the observations of the time histories and spectral evolution of the detected events provided by the different instruments in different energy ranges. Short Gamma-Ray Bursts (< 2 s) have 10 ms structure in their time histories. They have harder energy spectra than the long (> 2 s) events. Evidence of the existence of four differently behaving componenents in gamma-ray burst spectra is discussed. Statistical properties of the gamma-ray burst sources based on the 5 years of observations with (∼ 10−6 erg/cm2) sensitivity as well as the results of high sensitivity (∼ 10−8 erg/cm2) search for Gamma-Ray Bursts within the SIGMA telescope field of view are reviewed.

More than 180 gamma-ray bursts have been observed by the PHEBUS instrument aboard GRANAT observatory since its launch in December, 1989. A large database of the burst spectra in 0.1-100 MeV energy range has been accumulated that shows a wide variety of their evolution. Among the great majority of events displaying standard hard to soft evolution of spectra some bursts exhibit unusual behaviour with hardness ratio rising with time. We present here the brightest examples for both types of events and discuss also the question of the presence of lines in burst spectra.