Fluidized bed reactor is commonly utilized in industry due to their excellent solid mixing, heat and mass transfer properties. Fluidized bed reactor is best to be operated in bubbling flow regime. This study highlights the model development for hydrodynamics study on the effect of steam inlet velocity and solid initial bed height to the solid fluidization in the fluidized bed gasifier using Eulerian-Eulerian multiphase model coupled with kinetic theory granular flow approach. From the simulation, it is observed that 3.5 Umf steam inlet velocity gives the best solid fluidization in the gasifier. The increase in solid initial bed height does not give significant improvement to the fluidization in the gasifier. However, at high initial bed height the expended bed become unsteady. Therefore, for this work solid initial bed height of 10 cm or below is much more suitable as it gives good fluidization in the gasifier while still maintaining the stability of the extended bed. © 2010 Asian Network for Scientific Information.