The developed CoMo/Al-HMS nanocatalyst (3.4 wt% Co and 9.4. wt% Mo) via supercritical methanol-carbon dioxide deposition was characterized by different techniques (adsorption-desorption of nitrogen, oxygen chemisorption, XRD, TPR, TEM and EDAX) and tested in the hydrodesulfurization of dibenzothiophene. The results indicated that supercritical impreganation of Co and Mo into support has positive effect on the catalyst activity. The higher catalyst performance is attributed to higher and more uniform dispersed deposition of the catalytic metals on the support with increased active surface area. The results of hydrodesulfurization of dibenzothiophene demonstrated enhance activity for the new catalyst in terms of increased conversion, selectivity and rate constant. Furthermore, addition of aromatics in the feed showed less inhibition effect of CoMo/Al-HMS nanocatalyst with respect to the commercial catalyst. (C) 2009 Elsevier B.V. All rights reserved.