The effect of tungstate ion on the electrochemical behavior of tungsten has been investigated using direct current potentiodynamic polarization. As the concentration of tungstate ion increases, the anodic current increases and shifts to less noble potentials. This unexpected result is attributed to the solubilization (via polymerization) of tungstate ions generated via W dissolution, by the tungstate species previously introduced into solution. With the iodate ion as a model oxidizer, the dissolution current was found to increase in the presence of added tungstate ions. This suggests that tungstate ions can facilitate the metal dissolution during tungsten chemical mechanical polishing. © 1999 The Electrochemical Society. All rights reserved.