The aim of this work is to investigate whether the PC-SAFT (pertubed chain-statistical associating fluid theory) equation of state can describe the vapor-liquid equilibria for carboxylic acid-containing systems. Carboxylic acids, unlike many other associating compounds, have a strong tendency to dimerize in the vapor phase at normal conditions resulting in strong nonideal behavior at low pressures. In this work, we will focus on five binary systems {water + acetic acid}, {water + propionic acid}, {water + acrylic acid}, {acetic acid + propionic acid}, and {acetic acid + acrylic acid} due to their importance for chemical industries. The study was performed in a systematic method: first, the PC-SAFT equation has been applied to the pure carboxylic acid in order to determine the pure molecular parameters and then to the binary system. In this case, the interaction parameter k(ij) was determined using liquid-vapor equilibria data. This work shows that the PC-SAFT equation of state is able to represent the pure carboxylic acid as well as mixtures containing carboxylic acid.