The cubic-plus-association (CPA) equation of state (EoS) is applied in this study to binary aqueous mixtures containing hydrocarbons. The CPA EoS combines the Soave-Redlich-Kwong (SRK) cubic equation of state for the physical part and perturbation theory for the chemical (association) part. Rigorous expressions for the contribution of the association term to the pressure and to the chemical potential, which do not include any derivatives of the mole fraction of molecules i not bonded at site A (X-Ai), are presented. Three different association models for water have been considered depending on the number of hydrogen bonding sites per water molecule : the two-, three-, and four-site models. Successful correlation of both vapor pressures and saturated liquid volumes is obtained with all three models. However, satisfactory correlation results of the mutual solubilities of water/aliphatic hydrocarbon systems are obtained only with the four-site model using a single interaction parameter (k(ij)) in the attractive term of the EoS. A generalized expression of k(ij) as a function of the molecular weight of the members of the homologous series is presented, something that allows CPA to be used as a predictive tool. Very satisfactory prediction results are obtained, comparable to the correlation ones of the SAFT EoS for the water solubility in the hydrocarbon-rich phase and orders of magnitude better for the hydrocarbon solubility in the water-rich phase. Satisfactory predictions are also obtained for the vapor-phase compositions and the three-phase equilibrium pressures.