Abstract：The palladium （Ⅱ）-thiourea-potassium iodate complex had a sensitive adsorptive wave in NH3·H2O-NH4Cl buffer solution at pH 8.20, with peak potential at about -0.42 V （vs. SCE）. The second derivative peak current of this wave was linear to the mass fraction of palladium in the range of 0.60-2.20 μg/L（r = 0.998 8）, and the detection limit was 0.30 μg/L. Several electrochemical methods proved that this adsorptive wave was complex adsorptive wave, and the electrode process was irreversible. The effect of several ions on peak current （Ip''） was investigated. In the determination of 0.1 μg/L palladium, the tolerant amount of Mo(Ⅵ), Pb2+, Cd2+ and Mn2+ was low （0.01 μg/L, 0.08 μg/L, 0.1 μg/L and 0.2 μg/L, respectively）, but the tolerant amount of other testing cations was high. When the content of Mo(Ⅵ), Pb2+, Cd2+ and Mn2+ was beyond the tolerant amount, the interference could be eliminated by adding tartaric acid and dimercaprol for masking. The proposed method was applied to the determination of trace palladium（Ⅱ） in aluminium alloy. The relative standard deviation （RSD） of determination results was 2.1 %, and the recoveries of standard addition were 95 %-102 %.
