Nonsulfided alumina supported Ni, Co, Mo, NiMo, and CoMo hydrotreating catalysts were synthesize. The TEM results indicated low dispersions of the active metals for Mo, NiMo, and CoMo, samples but significantly higher dispersion for the Ni sample. The effect of calcination and reduction on the hydrogen uptake capacity of the samples was investigated. The H-2-chemisorption and XPS results together showed that the precalcination step had a detrimental effect on the hydrogen absorption of the Ni sample formation of stable metal oxides. The XPS results revealed that the metal oxides of all calcined samples reached with the alumina support to form very stable spinels. Futher, the positive effects of a hydrogen atmosphere during the reduction, on the hyderogen uptake of the samples were cinfirmed by H-2-chemisorption measurements. Finally, the heats of adsorption (Delta H) of hydrogen for the Ni and Co samples were calculated to be 140 and 98 kJ mol(-1), respectively.