The kinetic experiments were carried out at 1200°C to develop some effective slags for removing Pb and Ni from liquid copper, and the effects of slag composition on the extent and on the rate of the removal were examined. It was found that the slag viscosity and the activity coefficient of PbO were lowered by the addition of B2O3. For slags containing B2O3, the reaction almost finished within 5 minutes after adding slag and the degree of removal was more than 90%. But the removal degree of Ni was not so high compared with that of Pb. Thus, Ni removal by oxidation was more difficult than Pb removal. For example, the removal degrees of more than 90% for Pb and of about 50% for Ni were obtained Cu2O-B2O3-Fe2 O3 slag. The change in metal composition during oxidation reaction could be explained by the couple reaction model.