An indium e zinc-oxide(IZO) based ionic/electronic hybrid synaptic transistor gated by field-configurable nanogranular Si O2 films was reported. The devices exhibited a high current ON/OFF ratio of above 107, a high electron mobility of w14 cm2V1s1 and a low subthreshold swing of w80 m V/decade. The gate bias would modulate the interplay between protons and electrons at the channel/dielectric interface. Due to the dynamic modulation of the transient protons flux within the nanogranular Si O2 films, the channel current would be modified dynamically. Short-term synaptic plasticities, such as short-term potentiation and shortterm depression, were mimicked on the proposed IZO synaptic transistor. The results indicate that the synaptic transistor proposed here has potential applications in future neuromorphic devices. An indium e zinc-oxide (IZO) based ionic / electronic hybrid synaptic transistor gated by field-configurable nanogranular Si O2 films was reported. The devices showed a high current ON / OFF ratio of above 107, a high electron mobility of w14 cm2V1s1 and a low subthreshold swing of w80 m V / decade. The gate bias would modulate the interplay between protons and electrons at the channel / dielectric interface. Due to the dynamic modulation of the transient protons flux within the nanogranular Si O2 films, the channel current would be modified dynamically. Short-term synaptic plasticities, such as short-term potentiation and shortterm depression, were mimicked on the proposed IZO synaptic transistor. The results indicate that the synaptic transistor proposed here has potential applications in future neuromorphic devices.