The intrinsic kinetics Of CO2 hydrate formation were investigated using a semi-batch stirred tank reactor equipped with a focused beam reflectance method (FBRM) probe for in situ particle size analysis. Experiments were carried out at temperatures ranging from 274 to 279K and pressures ranging from 1.6 to 3.0MPa. The experiments were designed to obtain the intrinsic rate constant using a modified version of the model of Englezos et al. (Chem. Eng. Sci. 42(1987a)2647) that incorporates the measured particle size data. It was found that the intrinsic rate constant for CO2 hydrate formation varied from 3.214 x 10(-3) to 6.423 x 10(-3) mol/m(2) Pas, with the minimum value occurring at roughly 277 K. (C) 2004 Elsevier Ltd. All rights reserved.