Cadmium is a toxic metal, which is primarily produced as a by-product from mining, smelting and refining of sulphide ore concentrates of zinc. Secondary cadmium is recovered from spent Ni-Cd batteries. Some cadmium is also recovered from zinc sinter plant fume, EAF dust, cadmium containing alloys, cadmium containing fluorescent materials, etc. In all cases cadmium is associated with some other impurities depending on the source. The hydrometallurgical processing is very effective for treating such materials because it can control the different levels of impurities. The most common lixiviant used to dissolve the desired metals is sulphuric acid. In the present paper, the hydrometallurgical processes have been described for the recovery of cadmium from various resources using sulphuric acid as the main lixiviant. The leach solution obtained has been purified using cementation or solvent extraction methods. The metal is then produced from the purified solution by electrowinning or precipitation with zinc dust and melting. (C) 2006 Elsevier Ltd. All rights reserved.