The effect of humidity and polyethylene oxide (PEO)polyethylene glycol (PEG) content on the actuator performance of cellulose/PEO-PEG microcomposites was studied. Upon blending 5% PEO-PEG, the maximum bending displacement of the actuator increased nearly twice compared to that of cellulose EAPap actuator. However, further increase of PEO-PEG content resulted in decreased actuator performance. This might be due to the increased intermolecular interaction by hydrogen bonding that reduces the mobility of the molecules. The actuator performance test showed that the increase in humidity level rather reduced the maximum displacement of the actuators. X-ray diffractogram and Fourier transform infrared spectrum analysis suggested a structural change of the microcomposites as well as disruption of cellulose/PEOPEG association attributed to the actuator performance degradation at high humidity level. POLYM. ENG. SCI., 50:1199-1204, 2010. (C) 2010 Society of Plastics Engineers