The electrochemical effects are important for ionic materials when subjecting to the external electrical field. TiO2 is a mixed ionic-electronic semiconductor, and the ions, especially oxygen vacancies, are believed to be crucial for various phenomena such as resistive switching. However, directly experimental evidence of their correlations has not been observed. In this study, the correlation between the electrochemical effect and resistive switching in TiO2 thin film has been investigated by combining the Electrochemical Strain Microscopy (ESM) and conductive-Atomic Force Microscopy (c-AFM) under ambient air and Argon environments. The results have established direct relationship between the electrochemical reactions with the bipolar resistive switching in TiO2 thin films. (C) 2016 The Electrochemical Society. All rights reserved.