The main mass transfer processes of the ions in a vanadium redox flow battery and the temperature dependence of corresponding mass transfer properties of the ions were estimated by investigating the influences of temperature on the electrolyte properties and the single cell performance. A composition of 1.5 M vanadium solutions in 3.0 M total sulfate was selected and a range of − 10–50 °C was set as the operating temperature limits. It shows that the temperature effect on the concentration polarization of reactive substances and the ionic mobility of H+ in the membrane may be the main factor affecting the performance at low temperatures, while the diffusion coefficient and the ionic mobility of vanadium ions are dominant for the performance at high temperatures. The relation between the mass transfer properties of the ions in electrolyte and the battery performance was then clarified using a route map of the temperature effects.