Hydrodynamic properties of a hybrid fluidized-bed air-lift bioreactor were detd. The analyzed apparatus consisted of a 2-phase air-lift bioreactor with external circulation tube and a 2-phase liq.-solid fluidized-bed bioreactor. The circulation of a liq. was used to maintain the fluidization of solid particles in fluidized-bed part. The main advantage of the bioreactor is a lower shear force acting on the biofilm immobilized on fine particles in comparison to 3-phase fluidized-bed bioreactors. The way of calcn. of gas hold-up in the air-lift part and gas and liq. velocities in all zones of analyzed hybrid bioreactor was presented.