Alkyne-dicobalthexacarbonyl complexes are readily prepared by the reduction of cobalt bromide by Zn in the presence of alkynes in THF while bubbling carbon monoxide under ambient conditions. The complexes prepared in this way react with olefins to give the corresponding Pauson-Khand cyclopentenones in moderate to good yields. The alkyne-dicobalthexacarbonyl complexes can be also prepared in situ by