[en] The FIGARO II (French Italian GAmma, Ray Observatory) experiment designed to observe cosmic sources with a well established time signature is described. It consists of a large-area (3600 cm²) array of nine tiles of NaI(Tl), actively shielded against the environmental background, to be operated at high altitude by means of a stratospheric balloon for the detection of celestial gamma rays in the energy band 0.17-6.0 MeV. The performance of this experiment derived from calibrations with radioactive sources and flight data is presented. The actual sensitivity allows the detection of a pulsed signal with a flux of 5x10^-5 ph/(cm² s MeV) (≅ 6% of the Crab pulsar flux), in the whole energy band at 3 standard deviations in an observation time of 6 hours. (orig.)