Phthalide as an important value-added chemical can be fabricated through the hydrogenation of phthalic anhydride. However, the deactivation of metal supported catalysts for this reaction has limited its application. Herein, a series of NixCuy/Al2O3 alloy catalysts were prepared by a deposition-precipitation method and applied in the selective hydrogenation of PA to phthalide. Under mild reaction conditions (at 200 °C, 3 MPa H2), the optimal Ni9Cu1/Al2O3 catalyst shows the phthalic anhydride conversion of 91 % and phthalide selectivity of 97 %, respectively. Besides, this catalyst displays the good stability under five cycles without observing the obvious deactivation. The high efficiency of the Ni9Cu1/Al2O3 catalyst can be attributed to the electronic interaction of the two metals in NiCu alloy, which promotes the dissociation of H2 and suppresses the corrosion of alloy. This work reveals the electronic interaction between two metals, which provides a new avenue for rational design of alloy catalyst for selective hydrogenation of CO bonds. Display omitted •The optimized NiCu alloy catalyst shows high hydrogenation activity and stability.•The Ni9Cu1/Al2O3 catalyst exhibit synergistic effect of two metals in alloys.•The doping of Cu in Ni facilitates the activation of CO bond.