A combination of pyro- and hydro-metallurgical process has been proposed to selectively recover molybdenum, cobalt and aluminium from the spent hydrodesulphurization catalyst containing 12.3% Mo; 31.8% Al; 2.38% Co; 9.5% S and 2.9% C. Before a two stage alkali-acid leaching process to selectively target Mo, Co and Al from the uncrushed sample, the spent catalyst was roasted at different temperature. Characterizations of different roasted samples were carried out in order to understand the structural changes and dissolution behavior of spent catalyst. Mo was selectively separated and recovered from the leach liquor by carbon adsorption method; whereas, Al and Co were separated by an organo-phosphinic based extractant, Cyanex 272. In the whole process, 95.9% Mo, 89.6% Co and 39.8% Al was recovered from the spent catalyst.