A commercially available chelating extractant, LIX63, with the active component of 5,8-diethyl-7-hydroxydodecane-6-oxime was used to investigate the extraction of molybdenum and vanadium from sulphuric acid leach solution of spent hydrodesulphurisation catalysts containing 3 g/L Mo, 1 g/L V, 0.5 g/L Ni, 1 g/L Co, 0.2 g/L Fe and 10 g/L Al.molybdenum and vanadium were found to be extracted and separated completely from other metals in the solution at low pH of around 1.5.The loaded organic solution was easily stripped by 1 mol/L NaOH solution with excellent phase separation.After the precipitation of vanadium as NH4VO3 from the loaded strip liquor, molybdenum was recovered as pure sodium molybdate solution by further removing a small amount of vanadium remaining in the solution using Aliquat 336 at pH 8.5.The loaded Aliquat 336 was then stripped and regenerated using 1 M NaOH and 0.5 M NaCl solution.