Apparent molar volumes V-phi and apparent molar heat capacities C-p,C-phi have been determined for aqueous solutions of phenol (C6H5OH) and its sodium salt (C6H5ONa) at temperatures T from 278.15 to 393.15 K, at the pressure 0.35 MPa, and at molalities nt from 0.025 to 0.50 mol . kg(-1). We used a vibrating tube densimeter (DMA 512P, Anton PAAR, Austria) to determine the densities and volumetric properties, and a twin fixed-cell, power-compensation, differential-output, temperature-scanning calorimeter (NanoDSC 6100, Calorimetry Sciences Corporation, American Fork, UT, USA) to obtain the heat capacities. Infinite dilution partial molar volumes V-2(0) and heat capacities C-p,2(0) were obtained over the range of temperatures by extrapolation to m = 0 mol . kg(-1) on the fitted surfaces (V-phi, T, m) and (C-p,C-phi, T, m). Our results were combined with values of V-phi and C-p,C-phi from the literature for NaCl(aq), HCl(aq), and NaOH(aq) to obtain (Delta(r)V(m), T, m) and (Delta(r)C(p,m), T, m) for the proton dissociation reaction Of C6H5OH(aq). Surfaces representing (Delta(r)H(m), T, m), (pQ(a), T, m), and (Delta(r)S(m), T, m) where created by integration of our (Delta(r)H(m), m) surface using values for (pQ(a), m) and (PQa, m) at T = 298.15 K from the literature as integration constants. (C) 2003 Elsevier Science Ltd. All rights reserved.