Rotating disc voltammetry has been used to demonstrate that acetate ion is a catalyst for the hydration of carbon dioxide. In 0.05 M sodium chloride solution, the addition of 50 mM sodium acetate leads to an increase in the rate constant for the hydration of carbon dioxide from 0.9 to 8.9 s(-1) at 333 K. The rate of hydration decreases with increasing ionic strength and decrease in temperature. (C) 2008 Elsevier B.V. All rights reserved.