A capillary-driven heat transfer device, adapted to extract heat from a heat source and to release this heat to a cold source by means of a two-phase working fluid, includes an evaporator, having a microporous mass adapted to perform capillary pumping of fluid in the liquid phase, a condenser, a reservoir having an inlet and/or outlet port, a vapor communication circuit, connecting the outlet of the evaporator to the inlet of the condenser, and a liquid communication circuit connecting the outlet of the condenser to the reservoir and to the inlet of the evaporator. The reservoir includes multiple separate volumes that remain in fluid communication.