Non-noble intermetallic compounds have recently shown promising catalytic performances for the partial hydrogenation of alkynes and alkenes. In this work, the properties of alpha-Al4Cu9(110) toward the gas-phase hydrogenation of butadiene have been investigated at total pressures of 2-20 mbar and temperatures of 110-180 °C. The model catalyst is active and 100% selective to butenes. Moreover, although less active than Al13Fe4(010), which had been previously evaluated for the same reaction, it is more selective and more stable. The combination of catalytic tests with pre- and postreaction Auger electron spectroscopy measurements, and comparative tests with Cu(110), shows that copper governs the reaction on alpha-Al4Cu9(110). However, the lower activity of the (Curicher) sputtered Al4Cu9 surface with respect to the annealed one, and the differences between Al4Cu9 and Cu surfaces in terms of butene isomer distribution, butene conversion kinetics and sensitivity to poisons, demonstrate the unique character of the intermetallic compound.