In this Letter, we describe ionic effects on interfacial water structure next to the inner-surface of mesoporous silica, measured by Raman spectroscopy. Continuous desorption of water from pores was used to control pore filling fraction. Results show that Na+ and Cl- preferentially destroy the tetrahedrally coordinated structures in core water residing far from the interface. After capillary decondensation, the hydrogen-binding networks in the residual interfacial water are slightly and almost uniformly broken. Ions have almost no effect on the structure of the interfacial water film when the negatively charged pore surface is incompletely covered by water molecules. (C) 2012 Elsevier B. V. All rights reserved.