Résumé : The partial widths of the η′(958) decays into 2γ, ωγ, 3π0 and ηπ0π0 have been measured with the GAMS-2000 spectrometer at the 70 GeV IHEP accelerator. Upper limits for the η′ decays into 3γ, π0γγ, 2π0 and 4π0 have also been obtained. The slope of a linear matrix element for the G-parity violating decay η′→3π0 has been determined. © 1987 Springer-Verlag.