NOVELTY - Method of anaerobically digesting organic material, involves (a) continuously fermenting a mixture of a hydrogen-producing anaerobic microorganism and a portion of the organic material in a bioreactor to produce hydrogen, (b) drawing gaseous hydrogen produced in step (a) from a headspace above the mixture in the bioreactor, (c) feeding another portion of the material having an organic load (OL) into the bioreactor to supplement the organic load of the material in the bioreactor and (d) removing a portion of digested material from the bioreactor.    USE - The method is useful for anaerobically digesting organic material into useful products such as hydrogen and methane.    ADVANTAGE - The method enables to improve the rate of anaerobic degradation due to the solubilization of the particulate matter, decrease odor generation and clogging problems, and enhance sludge dewatering.    DETAILED DESCRIPTION - Method of anaerobically digesting organic material, involves (a) continuously fermenting a mixture of a hydrogen-producing anaerobic microorganism and a portion of the organic material in a bioreactor to produce hydrogen, (b) drawing gaseous hydrogen produced in step (a) from a headspace above the mixture in the bioreactor, (c) feeding another portion of the material having an organic load (OL) into the bioreactor to supplement the organic load of the material in the bioreactor and (d) removing a portion of digested material from the bioreactor, where the step (a) involves intermittently sonicating the mixture up to 90% of the time and the step (c) is repeated or performed continuously and the step (d) is repeated or performed continuously, to obtain a hydraulic residence time (HRT) of the organic material in the bioreactor of 2-48 hours and an average rate of production of hydrogen in step (a) that is at least 20% of the average organic loading rate (OLR) when the rate of hydrogen production is measured in liters hydrogen per liter bioreactor volume per unit time (L/Lbioreactor.d) and the OLR is measured as g chemical oxygen demand ( COD) per liter bioreactor volume per unit time (g COD/Lbioreactor.d).