This set provides the data for the paper "Hydrodynamic investigations for a two-phase geothermal pipe" by J. Hagedorn, M. Wirth, B. Weigang, S.Kabelac. This data set contains the raw data of the measurements and simulation for the differential pressure of air as the working fluid. Furthermore, the raw data of the countercurrent flow of water and air are also listed. Acknowledgements: This research project was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) (Project-ID: 455199958)