The present invention relates to a Cu-based catalyst, a preparation process thereof and its use as the dehydrogenation catalyst in producing a hydroxyketone compound such as acetoin. Said Cu-based catalyst contains copper, at least one auxiliary metal selected from metal of Group IIA, non-noble metal of Group VIII, metal of Group VIB, metal of Group VIIB, metal of Group IIB and lanthanide metal of periodic table of elements, and an alkali metal, and further contains at least one ketone additive selected from a ketone represented by formula (II) and a ketone represented by formula (II′). Said Cu-based catalyst shows a high the acetoin selectivity as the dehydrogenation catalyst for producing acetoin. R1-C(═O)—CH(OH)—R2  (II) R1-C(═O)—CH(═O)—R2  (II′) In formulae (II) and (II′), each group is defined as in the description.