The effect of lead ions on pyrite/xanthate interaction was investigated by cyclic voltammetric and ex situ spectroelectrochemical techniques. At pHs 9.2, and 10.5 with lime as pH modifier, uptake of xanthate was promoted by the presence of Pb. The source of Ph - from solution or from contact with galena - was not material, and the effect was evident at Pb concentrations as low as 1 ppm. With soda ash as pH modifier, the effect of Ph was suppressed, perhaps due to formation of lead carbonate. The only xanthate product detected was dixanthogen, unless an initial potential less than -800 mV/SCE was imposed (when Pb2+ is reduced to Pb-0) and lead xanthate formed. The significance to selective flotation of sulphide ores is discussed.