A rigorous mechanistic model for predicting gas hydrate formation crystallization kinetics is presented and the special case of CO2 gas hydrate formation regarding CO2 recovery and sequestration processes has been investigated by using the proposed model. A physical model for prediction of secondary nucleation rate is proposed for the first time and the formation rates of secondary nuclei by crystal-crystal collisions and crystal-impeller collisions are formulated. The objective functions for simultaneous determination of nucleation and growth kinetics are presented and a theoretical framework for predicting the dynamic behavior of gas hydrate formation is presented. Predicted time variations of CO2 content, total number and surface area of produced hydrate crystals are in good agreement with the available experimental data. The proposed approach can have considerable application for design of gas hydrate converters regarding energy storage and CO2 recovery processes. (C) 2011 Elsevier Ltd. All rights reserved.