Abstract: The effects of the grinding method and grinding medium on the flotation performance of sulphide minerals have been reported in many literatures. In the current investigation, grinding and floatation experiments using mild steel and stainless steel rods were performed to examine the effect of grinding medium type and collector addition site on flotation of a Cu-Ni sulphide ore. Test work was conducted using a laboratory scale horizontal tumbling rod mill and a batch flotation cell. The observations from flotation with different media and addition sites were discussed in terms of water recovery, solid recovery and valuable mineral recovery. The chemical parameters, namely pH, redox potential (Eh) and dissolved oxygen (Do) levels were measured. Different grinding media had significant effect on slurry chemical properties and flotation performance of Nkomati ore. The results demonstrated that mild steel rods produced a higher recovery of Cu, Ni, and pyrrhotite, meanwhile a higher Fe amounts extracted by EDTA and a lower Do level than stainless steel rods. The effect of collector addition site was different for two kinds of medium. For mild steel rods, collector added in cell produced a higher Cu recovery. For stainless rods, collector added in the mill produced higher recoveries of Cu and Ni.