Carrier induced granular particles comprising Enterobacter cloacae and Citrobacter freundii were used to generate H-2 from sucrose in an anaerobic fluidized bed bioreactor. At a hydraulic retention time of 4.5 h, 95.8% of the sucrose was consumed and the rate of H-2 production reached 180 mmol H-2 1 h(-1). Biogas composition for H-2 and CO2 was 42 and 55%, respectively.