A cold model dual fluidized bed gasifier was designed and constructed to determine the hydrodynamic properties in a bubbling fluidized bed and in a riser using silica sand (260 gm) as the bed material to determine the optimum operating conditions for stable heat supply between the two reactors for the biomass gasifer operation. Solid circulation rate was measured as a function of gas velocity and solid inventory and the obtained data was correlated in terms of Froude number and a ratio of aeration and particle terminal velocities. Flow regimes and the axial solid holdup distribution in the riser were determined as a function of gas velocity and solid circulation rate.