A catalyst or precursor thereto comprising cobalt and/or a cobalt compound on a transition alumina support having a total cobalt content of at least 41% by weight and a cobalt surface area, after reduction, greater than 25 m.sup.2 per gram of total cobalt. The catalyst or precursor may be made by slurrying a transition alumina powder having a pore volume of at least 0.7 ml/g with an aqueous cobalt ammine carbonate complex and heating the slurry to decompose the complex.