The cementation of Ag+ ion onto a copper disk electrode has been studied. A new method was used to monitor the concentration of the Ag+ ion during the reaction. After a certain time, the cementation reaction, initiated in a dilute Ag+ solution, follows a first order kinetic relationship for several hours. The cathodic reduction of the Ag+ ion on a silver electrode and the anodic oxidation of a copper electrode under potentiodynamic conditions and the cementation reaction under intensiodynamic conditions were studied by impedance spectroscopy. Copper oxidation and Ag+ ion reduction reactions do not behave as simple redox reactions. Furthermore, a mechanism based on diffusion-convection towards a uniformly accessible electrode cannot be used to interpret the results obtained. The impedance measurements suggest that during cementation the electrode behaves like a partially blocked electrode with an evolving structure.