A mathematical model to simulate continuous gasification of coal particles in a bubbling fluidized bed reactor is presented. Material and energy balance equations have been formulated based on the 2-phase theory. Well-known correlations have been used to estimate the hydrodynamics. Devolatilization, heterogeneous reactions, and homogenous reactions have been included in the model. The model is used to simulate 29 experimental data sets from the published literature. The model predictions agree very well with the experimental data by adjusting the particle size. After establishing agreement with the data, the model was used to investigate influence of various operating parameters on overall performance (carbon conversion and the gross calorific value of generated gas). Thermodynamic analysis (using the minimization of the Gibbs free energy approach) has also been discussed. The presented model and results provide useful tool and insight on design and operation of fluidized bed gasifier.