  X-ray diffraction and Raman scattering measurements, and first-principles
calculations are performed to search for the formation of NaCl-hydrogen
compound. When NaCl and H$_{2}$ mixture is laser-heated to above 1500 K at
pressures exceeding 40 GPa, we observed the formation of NaClH$_{\textit{x}}$
with $\textit{P}$6$_{3}$/$\textit{mmc}$ structure which accommodates H$_{2}$
molecules in the interstitial sites of NaCl lattice forming ABAC stacking. Upon
the decrease of pressure at 300 K, NaClH$_\textit{x}$ remains stable down to 17
GPa. Our calculations suggest the observed NaClH$_{\textit{x}}$ is
NaCl(H$_{2}$). Besides, a hydrogen-richer phase NaCl(H$_{2}$)$_{4}$ is
predicted to become stable at pressures above 40 GPa.
