Dramatic differences in dissolution thermodynamics between nanoparticles and their bulk counterparts have been observed in which the particle size plays a crucial role. However, the quantitative influences of particle size on the dissolution thermodynamic properties of nanoparticles have not been systematically investigated. In this paper, the relations between dissolution equilibrium constant and dissolution thermodynamic functions with particle size were deduced by introducing the surface variables into the Gibbs function. Then the influence regularities of size on the dissolution equilibrium constant and the dissolution thermodynamic functions were obtained by measuring the solubilities of nano-Cu with different sizes in dilute acid at different temperatures. Theoretical analysis and experimental results reveal that with particle size decreasing, the dissolution equilibrium constant (K-0) increases, while the standard molar dissolution Gibbs energy (Delta(r)G(m)(0)), the standard molar dissolution enthalpy (Delta H-r(m)0) and the standard molar dissolution entropy (Delta S-r(m)0) decrease. Furthermore, when the diameter approaches or exceeds 20 nm, In K-0, Delta(r)G(m)(0), Delta H-r(m)0 and Delta S-r(m)0, present linear relations with the reciprocal of diameter, respectively. (C) 2018 Elsevier B.V. All rights reserved.