A novel slurry hydrotreating process is described which employs a hydrotreating catalyst of small particle size having a quantity of catalyst sites in excess of those required for reaction and/or adsorption of nitrogen compounds in the petroleum or synfuel feed being treated. The excess catalyst sites can therefore in effect be contacted with a low nitrogen or essentially zero nitrogen feed, allowing rapid hydrogenation of aromatics at low temperatures where equilibrium is favored. In a further aspect of the invention, the catalyst which contains adsorbed nitrogen is activated by high temperature denitrogenation.