The first HVE Tandetron™ with a nominal terminal voltage of 5 MV has been put into operation at the Universidad Auto´noma de Madrid (Spain) as part of their new IBA facility. The accelerator features a coaxial structure in which the all‐solid‐state power supply is constructed around the high‐energy acceleration tube, thereby avoiding the T‐shaped tank that has characterized the HVE Tandetrons™ so far. The new IBA facility covers a number of different ion beam analysis techniques including ERD using heavy‐element time‐of‐flight, RBS, as well as an external micro‐beam for PIXE. During installation, tests have shown a stable terminal voltage of 5.5 MV. The terminal voltage ripple was deduced to be below 6 × 10−6(RMS) for terminal voltages above 800 kV. Terminal voltage undershoot was measured to be 1.4 × 10−3for a ∼1 kW beam at 3 MV and recovered to 1 × 10−4within 800 ms. IBA experiments that require low energy hydrogen beams are supported by a stable terminal voltage down to 100 kV. © 2003 American Institute of Physics