Dissolution properties of copper oxide in aqueous solutions containing ethanolamine and/or ammonium fluoride have been evaluated at various pH ranges. The dissolution rate was strongly affected by the pH of the solution. The solution of ammonium fluoride showed good properties for the dissolution of copper oxide in the range of acidic conditions, whereas the solution containing ethanolamine showed a dissolution property within the basic condition. A mixture solution of ethanolamine and ammonium fluoride displayed enhanced dissolution property of copper oxide at acidic and basic conditions only. An expected synergy effect on the dissolution rate and selectivity could not be produced through a mixture of ethanolamine and ammonium fluoride in an aqueous solution. Copyright © 2011 John Wiley & Sons, Ltd.