The synthesis of NiMo/Al-HMS nanocatalyst (2.3 wt % Ni and 9.4 wt % Mo) via supercritical CO2-methanol deposition and conventional wet coimpregnation was investigated. The characterization of both catalysts by adsorption-desorption of nitrogen, oxygen chemisorptions, XRD, TPR, and TEM indicated that Ni and Mo highly and uniformly dispersed oil the Al-HMS support. The results of activity of the NiMo/Al-HMS nanocatalyst in the hydrodesulfurization of dibenzothiophene demonstrated higher conversion for the NiMo/Al-HMS nanocatalyst in contrast to conventional catalyst. The reaction rate constants at 330 degrees C for the NiMo/Al-HMS nanocatalyst and the conventional one were calculated to be 3.65 x 10(-5) and 2.20 x 10(-5) (mol cat. min), respectively. Moreover, the newly developed nanocatalyst is less inhibited than the conventional catalyst by aromatics such as toluene.