Multiphoton spectroscopy of monodeuterated water is employed to determine more than 210 new energy levels of HDO in the 25000–35000 cm−1 region. These new empirical energy levels are used to fit a potential energy surface (PES) valid between 20000 cm−1 and 35000 cm−1 . Using this PES and an accurate lower energy PES as starting points, an energy-switching surface is constructed which is capable of reproducing the whole HDO spectrum from 0 to 35000 cm−1 . This PES is used to calculate a line list for HDO which covers infra red, visible and near ultraviolet transitions.