Abstract: A process for the leaching of metals from highly oxidized laterite ores. The ore is admixed with an acidic aqueous medium, preferably a solution of sulfuric acid and the resulting mixture is treated with a sulfur reducing agent so as to reduce mineral species containing cobalt, nickel or manganese. The sulfur reducing agent may be an aqueous solution of sulfur dioxide or more preferably the sulfur dioxide is generated in situ by the reduction of alkali metal sulfite salt. The process is conducted at ambient temperature and pressure with the reduced mineral species being dissolved and subsequently recovered.