Sound velocities in aqueous solutions of citric acid were measured from 15 degrees C to 50 degrees C in 5 degrees C intervals, within the 0.1 mol . kg(-1) to 5.0 mol . kg(-1) concentration range. These sound velocities served to evaluate the isentropic and isothermal compressibilities, the apparent molar compressibilities, the isochoric thermal pressure coefficients, changes of the cubic expansion coefficients with pressure at constant temperature, the changes of heat capacities with volume and hydration numbers of citric acid in aqueous solutions. (C) 2013 Elsevier Ltd. All rights reserved.