We use non-adiabatic molecular dynamics simulations to investigate ionization dynamics of small water clusters with adsorbed hydrogen chloride. Hydrated hydrogen chloride appears either in its covalent or acidically dissociated forms. In both cases, the ionization dominantly leads to formation of chlorine radical independently whether the chlorine or water moieties are initially ionized. Alternatively, the neutral HCl molecule and OH center dot radical are formed. The neutral chlorine species departs from the cluster, leaving behind the positive charge localized on water or protonated water cluster. This observation is consistent with mass spectrometry experiments. Certain fraction of the charged clusters undergoes further fragmentation. (C) 2015 Elsevier B.V. All rights reserved.