Energy-selected electron-ion coincidence spectroscopy for the study of surface dynamics combined with synchrotron radiation (SR) was developed. The equipment consists of an electron gun, a cylindrical mirror analyzer (CMA), and a time-of-flight (TOF) ion mass spectrometer. A sample surface was excited by SR, and energy of the emitted electron was analyzed by the CMA. The TOF spectrum of the desorbed ions was measured taking the energy-analyzed electron signal as the starting trigger. The ions coincidently desorbed with the electron gave a characteristic peak in the TOF spectrum. The apparatus was evaluated on the basis of photoelectron–photoion coincidence (PEPICO) and Auger electron–photoion coincidence (AEPICO) measurements ofH2Ocondensed on gold foil. The results demonstrate that PEPICO and AEPICO combined with SR are powerful methods for investigating the ion desorption induced by core-level excitations. ©1997 American Institute of Physics.