We investigate the roles of TiN and Pt materials used as electrodes in resistive-switching HfO2 systems. Well-behaved reset operation is observed on condition Pt is used as anode, which together with the strong effect of thin insert layers (IL) indicates that the reset switching is favored at the HfO2\Pt interface. However, switching properties are hampered by yield and reliability issues associated to oxygen runaway at forming operation and caused by the Pt permeability to oxygen. TiN\HfO2\(IL)\Pt cells show better reliability due to improved oxygen buffering. The non-polar, unipolar and bipolar switching modes are discussed as originating from similar underlying physical mechanisms. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3575165] All rights reserved.