Transport and thermodynamic properties were studied for the complex metallic compound $\beta \text{−}{\mathrm{Al}}_3{\mathrm{Mg}}_2$, composed of 925 atoms per unit cell. $\beta \text{−}{\mathrm{Al}}_3{\mathrm{Mg}}_2$ exhibits bulk superconductivity below $T_c=0.87\mathrm{K}$. An exponential temperature dependence of the specific heat well below $T_c$ indicates BCS-like behavior with a nodeless gap of width ${\Delta }_{\mathit{BCS}}\left(0\right)\approx 1.5\mathrm{K}$. The coherence length is derived as ${\xi }_0=4.85\times {10}^{-8}\mathrm{m}$ and the Ginzburg Landau parameter ${\kappa }_{\mathrm{GL}}\approx 13$, characterizing $\beta \text{−}{\mathrm{Al}}_3{\mathrm{Mg}}_2$ as a type II superconductor. Superconductivity in $\beta \text{−}{\mathrm{Al}}_3{\mathrm{Mg}}_2$ occurs in the absence of inversion symmetry of the crystal. Surprisingly, in spite of the rather complex crystal structure of $\beta \text{−}{\mathrm{Al}}_3{\mathrm{Mg}}_2$, physical properties turn out to be quite simple.

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