Metal hydrides $M{\mathrm{H}}_x(x\le 2$) with low hydrogen content are not expected to show high-$T_{\mathrm{c}}$ superconductivity owing to the low hydrogen-derived electronic density of states at Fermi level and the limited hydrogen contribution to electron-phonon coupling strength. In this Letter, we report on the successful synthesis of a novel bismuth dihydride superconductor, Cmcm-${\text{BiH}}_2$, at approximately 150 GPa, and the discovery of superconductivity with $T_{\mathrm{c}}$ about 62 K at 163 GPa, marking the first instance of superconductor among the $M{\mathrm{H}}_2$-type metal dihydrides. Cmcm-${\text{BiH}}_2$ adopts a unique host-guest type structure, in which the Bi atoms via weak Bi-Bi covalent bonds form a three-dimensional open-channel framework that encapsulates ${\mathrm{H}}_2$-like molecules as guests, thereby broadening the structural diversity of hydrides under high pressures. The occurrence of superconductivity is evidenced by a sharp drop of resistivity to zero and the characteristic downward shift of $T_{\mathrm{c}}$ under applied magnetic fields. Notably, Cmcm-${\text{BiH}}_2$ remains stable down to at least 97 GPa during decompression, with the calculated lowest pressure for dynamic stability of 10 GPa. In-depth analysis reveals that the covalent bismuth open-channel structure forms metallic conduction channels, dominates the electronic states near the Fermi level, and contributes approximately 51% of the total $\lambda$ in Cmcm-${\text{BiH}}_2$, distinguishing it from known high-pressure hydride superconductors. These findings highlight the critical role of nonhydrogen elements in producing superconductivity and open new avenues for the design and optimization of high-$T_{\mathrm{c}}$ hydride superconductors.

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• High-pressure studies
• Hydrides
• Superconductors
• BCS theory
• Density functional theory
• Pressure techniques
• X-ray diffraction