A coal particle model is developed to investigate the thermochemical processes of gasification for underground coal applications. The chemical reactions are defined with an Eddy Break up (EBU) model for controlling the reaction mechanisms and the study is particularly focused on identification of the important kinetic parameters, which control the consumption rate of coal mass. As an initial validation, the coal particle oxidation based on the experimental results is used for comparison. The gasification reactions are subsequently applied for the thermochemical process investigation, and the results show that the best agreement of coal oxidation is achieved by the pre-exponent factor (A) of 0.002 and 85500, for the reactions, R2 (C + O-2 = CO2) and R3 (C + 0.5O(2) = CO), respectively. The kinetic parameters for the gasification process of coal particle leading to the syngas production are also optimised. The results show that the production of H-2 and CO is controlled significantly by the level of oxygen concentration in the char reactions. However, their chemical rates are strongly dependent upon the reaction zones. For example, CO is produced in both the oxidation and reduction reaction zones, while H-2` production is dominated in the reduction zone. Spatio-temporal distributions of the gas species along with the coal particle temperature provide additional information for further development of UCG modelling. Ultimately, the model gives a good guideline with the associated thermochemical processes that can help developing advanced coal gasification technology and lead to improved syngas quality.