  We report the discovery of superconductivity in noncentrosymmetric NbReSi,
which crystallizes in a hexagonal ZrNiAl-type crystal structure with space
group $P\bar{6}2m$ (No.~189). Bulk superconductivity, with $T_c$ = 6.5 K was
characterized via electrical-resistivity, magnetization, and heat-capacity
measurements. The low-temperature electronic specific heat suggests a fully
gapped superconducting state in NbReSi, while a large upper critical field of
$\mu_0H_\mathrm{c2}(0)$ $\sim$ 12.6 T is obtained, which is comparable to the
weak-coupling Pauli limit. The electronic band-structure calculations show that
the density of states at the Fermi level are dominated by Re and Nb
$d$-orbitals, with a sizeable band splitting induced by the antisymmetric
spin-orbit coupling. NbReSi represents another candidate material for revealing
the puzzle of time-reversal symmetry breaking observed in some Re-based
superconductors and its relation to the lack of inversion symmetry.
