The kinetics of conditioning of sulphide minerals was investigated and a rate equation for xanthate adsorption on pyrite and chalcopyrite is suggested. As expected, it was observed that dissolved oxygen has a strong influence on the pulp potential and the rate of xanthate adsorption on a sulphide mineral surface. As the concentration of dissolved oxygen is increased, the pulp potential and the rate of xanthate adsorption is also increased. Differential analysis of the kinetic rate equation was used to determine the reaction order with respect to oxygen. The rate of xanthate adsorption on pyrite was found to be in the order of 0.5 at pH 6 and 0.7 at pH 9 with respect to oxygen. In the case of chalcopyrite, the order of the adsorption reaction with respect to oxygen was found to be 0.6 at pH 6 and pH 11.5. Integral analysis of the rate equation demonstrated that the order of the xanthate adsorption reaction with respect to xanthate is about 0.5 for pyrite.