Recently, a bioprotonic field-effect transistor with chitosan nanowire channel was demonstrated [Nat. Commun., 2011, 2, 476]. Here, it is interesting to find that solution-processed chitosan films with a large electric-double-layer (EDL) specific capacitance can also be used as the gate dielectrics for low-voltage individual SnO₂ nanowire transistors. The field-effect electron mobility, current on/off ratio and sub-threshold slope of such a hybrid SnO₂ nanowire device is estimated to be 128 cm² V⁻¹ s⁻¹, 2.3 × 10⁴ and 90 mV per decade, respectively. Such low-voltage nanowire EDL transistors gated by chitosan-based proton conductors are promising for nanosensors and bioelectronics.