Cobalt/nickel residue has a high content of arsenic, and it poses a great threat to humans. It is absolutely necessary to treat the residue. In this study, the leaching of cobalt/nickel residue using alkali at atmospheric pressure was reported. The results showed that the optimum condition was as follows: 16 g of oxidant reagent, alkali concentration of 5 mol/L, reaction temperature of 80°C and reaction time of 2 h. Under those conditions, the leaching ratios of arsenic and zinc reached about 99% and 87%, whereas cobalt, copper and nickel remained non-dissolved. Based on thermal analysis and kinetics calculation, the activation energy of the leaching process was 42.06 kJ/mol, and the reaction order was 2.77. This work effectively recovered arsenic from this hazardous residue, greatly reducing environmental pollution. It also laid a solid foundation for further comprehensive recovery of valuable metals from the zinc metallurgy process.