In this work, the mechanical deformation of ionic electroactive polymer (IEAP) based tri-layer micro-actuator subjected to an electrical excitation and mechanical payload is presented. A detailed study on the electrical response of the microactuator during charging and discharging process is investigated. Electrical charges, capacitance and resistance of the simplified equivalent electrical circuit are analyzed. The results have shown that, the micro-actuator exhibits a linear behavior for applied voltage lower than 1V. Beyond that, non-linearities appear and are related to the discharging process, especially the corresponding electrical resistance which increases in a non-linear way. Moreover, accumulated electrical charges depend on the previously applied voltage and are not totally restored during the discharging process. The results of this study are illustrated with experimental and theoretical results.