The enthalpies of dilution Of L-cystine in solutions of two strong alkalis and one strong acid have been determined by isothermal flow-mix calorimetry at the temperatures 298.15 K, 303.15 K, 308.15 K, 313.15 K and 318.15 K. Equations of apparent enthalpies of dilution have been obtained from the experimental data in terms of the improved McMillan-Mayer theory. Enthalpic interaction coefficients, h(2), h(3), and h(4), are obtained and the values of pair-wise enthalpic interaction coefficient, h2, discussed in the light of solute-solute and solute-solvent interactions. (c) 2004 Elsevier B.V. All rights reserved.