High arsenic levels in nickel sulphide concentrates can often present technical and environmental problems at the smelter. In some ores a flotation separation between the nickel sulphides and the arsenide minerals is required in order to meet smelter specifications for arsenic. There is very little information in the literature about such separations and the flotability of nickel arsenides in general. Data are presented here from a single mineral flotation investigation into the flotability of niccolite (NiAs), one of the key nickel arsenide minerals present in nickel sulphide ores in Australia. Niccolite is only weakly flotable with xanthate collector at pH 9 and this behavior is independent of the grinding environment. This suggests that high arsenic levels in nickel concentrates are not due to niccolite flotation, but are more likely to be due to flotation of more floatable arsenic-bearing minerals such as gersdorffite. Cyanide diminishes the poor recovery of niccolite further. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.