ESA/ESTEC funded two-phase heat transport activities for spacecraft thermal control started in the mid 1980's. A number of different two-phase loops, using either a mechanical pump or driven by a capillary pumped evaporator, were designed, assembled and tested successfully in the past years. The transported power levels were from a few hundred watts up to 10 kW over distances of some meters up to several tens of meters. The working fluid was either Freon or Ammonia.Within ESA's Technology Demonstration Programme (TDP1), a first two-phase experiment (TPX) for flight as a GAS-payload on the US Shuttle was designed and has been successfully flown on STS-60 in February 1994.The article will present the ESA/ESTEC funded two-phase heat transport activities undertaken in the last years, namely the development of a mechanically pumped and a capillary pumped two-phase heat transport system, and discuss the different activities currently performed: the definition of an engineering model of a capillary and a mechanically pumped two-phase loop, the development of a capillary pumped two-phase loop breadboard for the thermal control of the laser head of an earth observation instrument, requiring the removal of up to 230W with a required temperature stability of +/- 1K, using radiators which are subjected to a changing thermal environment, the development of a high-efficiency, low-pressure drop two-phase condenser. Furthermore, results of the first European in-orbit demonstration of two-phase heat transport technology will be shortly discussed.