the effect of na3po4 and the mixture of benzotriazole (bta) and na3po4 (sp) on the corrosion of copper in 17?wt% (0.534?mol/l) tetra-n-butylammonium bromide (tbab) aerated aqueous solution has been investigated by means of weight-loss test, potentiodynamic polarization test, electrochemical impedance spectroscopy (eis), and scanning electron microscopy/energy dispersive x-ray techniques. the experimental results showed that a dosage of na3po4 stimulated the copper corrosion, and the corrosion rate increased with increasing na3po4 concentration, whereas the mixture of bta and na3po4 could protect copper in aqueous tbab solution. the inhibition action of the mixture of bta and na3po4 on the corrosion of copper is mainly due to the inhibition of the anodic process of corrosion. the inhibition efficiency of a mixture consisting of 2?g/l bta and 1?g/l na3po4 was about 96%. the mixture of bta and na3po4 inhibits the corrosion of copper better than bta by itself, indicating that na3po4 has a synergistic role with bta on the corrosion inhibition of copper in tbab aqueous solution.