  Crystals of superconducting Mo$_{8}$Ga$_{41}$ ($T_{\text{c}}=9.8$ K) and
Mo$_{\text{8-x}}$V$_{\text{x}}$Ga$_{41}$ limited solid solution
$(x_{\text{max}}=1.9(2))$ have been grown from the high-temperature Ga flux and
confirmed to have the V$_{8}$Ga$_{41}$ type of crystal structure at room
temperature. Thermodynamic and transport measurements as well as electronic
structure calculations were performed to investigate both normal- and
superconducting-state properties of Mo$_{8}$Ga$_{41}$. The discontinuity in the
heat capacity at $T_{\text{c}}$,
$\Delta{}c_{\text{p}}/\gamma_{\text{N}}T_{\text{c}}=2.83$ in zero magnetic
field, indicates a much stronger electron-phonon coupling than in the standard
BCS limit. From the heat capacity data, we estimated the electron-phonon
coupling constant $\lambda_{\text{ep}}=0.9$. The upper critical field is
$\mu_{0}H_{\text{c2}}(0)=8.3$ T, while the lower one is only
$\mu_{0}H_{\text{c1}}(0)=131$ Oe. The upper critical field of Mo$_{8}$Ga$_{41}$
exhibits a clear enhancement with respect to the Werthamer-Helfand-Honenberg
prediction, consistent with the strong electron-phonon coupling. The
Mo$_{\text{8-x}}$V$_{\text{x}}$Ga$_{41}$ limited solid solution also exhibits
superconducting properties, and the critical temperature $T_{\text{c}}$ is
reduced only slightly with increasing $x$.
