Perturbed-chain statistical associating fluid theory (PC-SAFT) is coupled with Young-Laplace equation to investigate and represent fluid-phase equilibria in nanosize pores. The calculated pure-substance properties at capillary condensation (critical temperature, critical pore radius, surface tension, condensed-phase equilibrium pressure, and saturated densities) are found to be consistent with experimental data, theoretical models, and molecular simulation. The information obtained for pure substances can then be applied to predict the phase equilibria of fluid mixtures in porous mediums. The promising results presented in this work establish a strong platform for further development of an effective model toward engineering applications in real settings of confined fluids such as chemical systems encountered in unconventional reservoirs (e.g., shale oil and shale gas). (C) 2015 Elsevier B.V. All rights reserved.