Abstract The selective hydrogenation of trans-4-phenyl-3-butene-2-one over Ru/g-Al2O3 stabilized with triphenylphosphine was investigated in the presence of diamine and base. It was found that 1,2-diphenylethylene-1,2-diamine (DPEN) was the best modifier among the investigated diamines. Both DPEN and KOH not only promoted the selectivity of the C O bond hydrogenation, but also accelerated the …