The validation of the S5P TROPOMI L2_SO2 sulphur dioxide plume height is based on satellite-to satellite comparisons, during large enough volcanic eruptions, with the Metop-B/C IASI “SO2_vertical_level” product, i.e., the retrieved vertical level of the SO2 plume, for the morning (AM) observations. Overall, TROPOMI shows lower SO2 layer height retrievals compared to the combined IASI/Metop[B&C] SO2 plume height observations by ~35 %, equivalent to a mean SO2 layer height difference of 3 km. In more significant volcano eruptions with robust and overlapping SO2 plumes between the involved instruments, the discrepancies are lower (~20 %) and equivalent to approximately 1.5 km. HYSPLIT airmass forward and backward trajectories are also employed as a validation tool of the S5P TROPOMI SO2_Layer_Height observations. Results indicate a good agreement between the altitude of trajectories, the altitude, and location of the plume with discrepancies of approximately 500 m.