Biomaterials gelatin is used as the dielectric layer in this work to develop metal/gelatin/Tungsten (W) RRAM devices, with silver (Ag), copper (Cu), W, and gold (Au) as the top electrode (TE) to study the effects of electrode metals on device characteristics. All types of the RRAM devices exhibit bipolar resistive switching characteristics with diverse performances. The work function difference between the TE and bottom electrode (BE) metals is found to play a profound role in determining the characteristics of the devices and even reversing the set and reset processes. The devices with larger work function difference between the TE and BE metals have higher and more stable on/off resistance ratio. The Ag/gelatin/W devices exhibit a relatively stable switching behavior with an on/off resistance ratio of >10(2), while that with Au TE exhibits a reversed set and reset processes with a high on/off resistance ratio of >10(5) owing to the large positive work function difference between Au and W. Metallic conductive filaments are confirmed to be responsible for the switching behaviors of the devices experimentally, and what metal element in the conductive filaments is determined by the work function difference of the metals used for the top and bottom electrodes. (C) 2018 The Electrochemical Society.