The temperature dependence of outer hair cell motility-related gating current and capacitance was evaluated under whole-cell voltage clamp. Temperature change caused a shift of these voltage-dependent functions along the voltage axis, with a decrease in temperature causing a negative shift in the voltage at peak capacitance (Vpkcm) of 19.2 mV per 10 degrees C. Gating current kinetics showed only mild temperature dependence, the Q10 being about 1.5. Temperature is speculated to affect outer hair cell (OHC) mechanical gain and frequency response by alterations in lateral membrane viscoelastic properties. Such temperature-dependent effects on the OHC may mediate known temperature effects on in vivo cochlear physiology.