Engineers often demand the availability of easy correlations without difficult and time-consuming calculations. Up till now, there has been a lack of such correlations for mixtures of CO2 + ionic liquids. This work proposes a correlation to predict CO2 solubility in 27 common ionic liquids. The main advantages are its simplicity and minimal input data, namely temperature and pressure. The ionic liquids investigated ranged within a variety of families, having various anions and cations. Compared with the popular engineering models of Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK), the present correlation is much easier to use, yet it is also more accurate (PR, SRK and the proposed model had AARD% values of 43.5%, 443% and 4.9%, respectively for a total of 3073 data), even when binary interaction coefficients of PR and SRK are optimized to experimental data (AARD% values of 17.2%, 16.9% and 4.9% for PR, SRK and the proposed model, respectively). (C) 2013 Elsevier B.V. All rights reserved.