Reliable heat exchangers capable of transferring heat at low driving temperature differences are key to energy efficient processes. In this paper, heat transfer and fluid dynamics of hydrophobic nanoparticle (HBNP) coated tubes are investigated in a steam-heated single-tube thermosiphon reboiler and compared to experimental results of standard stainless steel tubes. In comparison to the bare tube, the coated tube showed higher heat transfer and circulation rates as well as an improved stability of the circulating flow. The stability of the coating was verified in a long-term stability test.