This article proposes a new method to fabricate the ionic polymer metal composite (IPMC) actuator with a preshaped form by a simple thermal treatment process. The effects of the thermal treatment process on the properties of the actuator such as stiffness, displacement, resonance, and generating force are analyzed. To verify the effect of the thermal treatment process on the generation force of the actuator, the four-fingered gripper using the proposed method is designed, fabricated, and compared with an unheated actuator. Experimental results show that thermally treated IPMC actuators have an improved generatingforce compared with that of unheated actuators. POLYM. ENG. SCI., 52:19911997, 2012. (c) 2012 Society of Plastics Engineers