The mobility of photoelectrons (mu(e)) was determined by measuring the transient photocurrent induced by electron photodetachment from rubidium anions (Rb-) in liquid tetrahydrofuran (THF) in the temperature range of 180-296 K. Electrons were generated by photoexcitation of Rb/THF solutions by 532 nm laser pulses. The measured transients consisted of a fast component (similar to 1 mu s) followed by a slow decay (similar to 10-100 mu s). Negative photocurrent was observed at high temperatures and large concentrations of the Rb ions. This unusual behavior is interpreted by taking into account the recombination and dissociation reactions involving the photoelectrons (e(-)) and rubidium ions (Rb+ and Rb-). The equilibrium constant of electron-cation dissociation was found to increase by an order of magnitude upon cooling the Rb/THF solution from 296 to 198 K. The mobility of the photoelectrons was found to be associated with an activation energy of 5.9 kJ mol(-1).