  A class of iridium hydrides, IrH_x (x=0.5, 1-4, 6), is calculated at
ab-initio level using the DFT. A number of hydrides are predicted to stabilize
in the excess hydrogen environment and upon compression. The threshold pressure
for thermodynamical stabilization is calculated to ~5 and ~14 GPa at which,
respectively, a trihydride (P6_3mc) and a dihydride (Ibam) stabilize with
respect to decomposition into pure element. The dihydride (Ibam) is calculated
to stabilize dynamically at P~14 GPa and the trihydride at P > 25 GPa. In both
the di- and trihydride iridium atoms form short directional contacts with
hydrogens, typical for covalent bonds. The trihydride exhibit molecular
character and its relative stability is calculated to be higher than that of
the dihydride, at least up to approx. 75 GPa.
