Dehydrogenation of 1,4-butanediol to 2,3-dihydrofuran over kaolin-supported Co and Co-Au catalysts has been investigated. Catalytic test and XRD analysis show that the presence of metallic cobalt with hexagonal structure is favourable for selectivity to 2,3-dihydrofuran of the reaction studied. It was established by XPS method that an optimal for the reaction selectivity Co-0/Co2+ ratio in Co/kaolin and Co-Au/kaolin catalysts exists. Quantum chemical calculations suggest that the initial step of 1,4-butanediol dehydrogenation on cobalt catalyst surface may be the cleavage of O-H bond to form alkoxide species on Co2+ ion. Based on the effect of metallic and ionic cobalt on the catalyst selectivity, it could be presumed that both cobalt species are involved in the rate-determining step in dehydrogenation of 1,4-butanediol into 4-hydroxybutanal intermediate. (C) 2004 Elsevier B.V. All rights reserved.