Abstract: A carbon paste electrode chemically modified with alkyl tertial amine (N₂₃₅) is used for the selective accumulation of gold (Ⅲ). The calibration plots are linear for the 0.1~10mgL^-1 range and the detection limit is 0.07mgL^-1 This electrode has been used to measure gold concentration in soma mineral samples without preisolation. The preparation and the electrochemical properties of the electrode, and the mechanism of extraction and activation are studied.