The interfaces between metal electrodes and the oxide in TiO2-based memristive switches play a key role in the switching as well as in the I–V characteristics of the devices in different resistance states. We demonstrate here that the work function of the metal electrode has a surprisingly minor effect in determining the electronic barrier at the interface. In contrast, Ti oxides can be readily reduced by most electrode metals. The amount of oxygen vacancies created by these chemical reactions essentially determines the electronic barrier at the device interfaces.