Abstract: In acidic phenylthlourea medium (pH2.2), by using single sweep polarography, gold can produce a sensitive cathodic polarographic wave at - 0.3V (vs. SCE). There is a linear dependence of wave height on gold concentration over a range of 5 ×10^-8-3×10^-6M. The method is good in selectivity and stability. After seperating and concentrating trace amounts of gold by the active carbon adsorption method, the method has been successfully applied to the determination of trace gold in ores.The mechanism of the polarographic wave was studied by a number of techniques. It was shown that phenylthiourea (PT) could be oxidized by Au(Ⅲ) to form sym-diphenyldithioformamidine (DF) which was strongly adsorbed by DME, then DFwas reduced at the electrode and produced a sensitive adsorptive polarographic wave. The mechanism may be represented as follows.