Organic single-crystal field-effect transistors based on dithiophene-tetrathiafulvalene (DT-TTF) showing a charge-carrier mobility of 1.4cm2/Vs were recently reported. These crystals were prepared from solution, making this material interesting for potential applications in low-cost electronics. Here, we studied the temperature dependence of a DT-TTF field-effect transistor as well as the transport properties of single DT-TTF crystals. We found that the field-effect mobility follows a thermally activated hopping model with activation energy values (Ea) of around 85meV, which is in agreement with the standard four-contact conductivity measurements performed on the single-crystals. In addition, the dependence of the Ea with temperature and of the threshold voltage with gate-induced charge suggest that the crystals do not contain deep impurity traps.