BACKGROUND Cyclic fatty carbonates can be obtained from epoxidized vegetable oils and CO2 under mild conditions. The main application of these bio-derivatives is the production of thermoset polymers and non-isocyanate polyurethanes. Castor oil has a different chemical structure from the other oils that have been used for carbonation. In this work, a kinetic model was developed for high CO2 pressure carbonation of epoxidized castor oil. RESULTS The highest epoxide group conversion (93%) was obtained at 130 °C and 480 min. However, the highest content of carbonate groups (1.5 carbonates/molecule) was obtained at 115 °C and 180 min. A kinetic model was proposed which included carbonation of epoxide as well as etherification of the oxirane ring as a competitive reaction. Both reactions were best fitted to pseudo-first-order kinetics. Activation energy of carbonation and etherification of the oxirane ring were estimated as 37.41 and 33.25 kJ mol−1, respectively. CONCLUSION Carbonated castor oil was produced from the epoxidized oil at 100–130 °C and a constant pressure of CO2 (0.5 MPa). Because of the polyfunctional character of the product, it could find applications as a monomer and as a synthetic building block for other bio-based chemicals. This product and the reaction pathway have not previously been disclosed. © 2016 Society of Chemical Industry