Droplet beam-laser ablation mass spectrometry has been developed for studies of molecules in a liquid after isolating them in the gas phase. A liquid droplet of an aqueous solution of NaI was introduced into a vacuum chamber, and its velocity and shape were obtained from stroboscopic images and a diffraction pattern of visible and UV lasers, respectively. The ions produced by irradiation of a UV laser onto the liquid droplet were almost identical to those produced from a liquid beam. The mechanism of ion formation is explained by the Coulomb-ejection model employed for ion ejection from the liquid beam. (c) 2005 Elsevier B.V. All rights reserved.