An attempt has been made to investigate and optimize the recovery of Ni and Al through sulphuric acid (3.0-5.5 mol/L) leaching under different operating conditions. From the leaching experiments, it was possible to extract 98.5% of NiO and 40.7% of Al₂O₃ under the conditions of 5.5 mol/L H₂SO₄, reaction time of 4 h, solid-to-liquid ratio 0.2 g/mL, temperature of 358 K, particle size <100 μm, 200-250 r/min with 5.0 g catalyst dosage. The leached liquor Al was separated by selective crystallization using 1.4 mol/L KOH and Ni was separated by selective precipitation using 0.3 mol/L H₂C₂O₄. From the studies, it is possible to recover around 97.9% of NiO having 98.3% purity, around 25% of Al₂O₃ was also recovered as alum-(K) having 99% purity and 14.7% of Al₂O₃ as a salt of Al-K-C₂O₄-SO_4. Sulphuric acid was found to be a suitable leaching agent for selective leaching and it was also observed that alum-(K) can be selectively crystallized from sulphate solutions. The study also indicated the effective extraction and recovery of nickel and aluminium which were well supported by characterization studies using TG-DTA/DTG and XRD techniques.