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The knowledge about pressure–volume–temperature–composition (PVTxy) properties plays an importantrole in the design and operation of many processes involved in CO2 capture and storage (CCS) systems.A literature survey was conducted on both the available experimental data and the theoreticalmodels associated with the thermodynamic properties of CO2 mixtures within the operation windowof CCS. Some gaps were identified between available experimental data and requirements of the systemdesign and operation. The major concerns are: for the vapour–liquid equilibrium, there are no data aboutCO2/COS and few data about the CO2/N2O4 mixture. For the volume property, there are no publishedexperimental data for CO2/O2, CO2/CO, CO2/N2O4, CO2/COS and CO2/NH3 and the liquid volume of CO2/H2. The experimental data available for multi-component CO2 mixtures are also scarce. Many equationsof state are available for thermodynamic calculations of CO2 mixtures. The cubic equations of state havethe simplest structure and are capable of giving reasonable results for the PVTxy properties. More complexequations of state such as Lee–Kesler, SAFT and GERG typically give better results for the volumeproperty, but not necessarily for the vapour–liquid equilibrium. None of the equations of state evaluatedin the literature show any clear advantage in CCS applications for the calculation of all PVTxy properties.A reference equation of state for CCS should, thus, be a future goal.