A high auriferous arsenopyrite floatability is desirable to maximise gold recovery in sulphidic refractory gold ore flotation. This study examines the adsorption properties of sulphidic refractory gold ore (2.58 g/t Au) in the presence of sodium isobutyl xanthate (SIBX) collector, under different pH and CuSO4 additions for maximum arsenopyrite and gold floatability. The SIBX adsorption studies showed that pH greatly influences SIBX adsorption on to the surface of sulphidic refractory gold ore. Very little effect of CuSO4 on SIBX adsorption in acidic environment (pH 5-5.5) was observed due to low copper ions adsorption. Better flotation recoveries of arsenopyrite (86%) and gold (91%) were achieved at the ore's natural pH (8-8.5) than under acidic or basic environments. Pyrite floated poorly (<20% recovery) for all pH conditions. Based on the studies, conditions for maximum collector adsorption, arsenopyrite and gold flotation recovery for the ore were established. (C) 2020 Elsevier B.V. All rights reserved.