The shortage of fresh water is one of the grand challenges that humans are facing. That requires the advent of seawater desalination and water treatment technology. As a promising novel method, the hydrate-based desalination has been developed and achieved considerable milestones in the past few years. However, the experimental data are still limited in the open literature. Therefore, in this study, thermodynamic equilibrium data of mixed CO₂-Cyclopentane (CP) hydrates in the presence of salts were investigated. In particular, MgCl₂ and CaCl₂, which are dominant cations in water caused hard water.