The possibility and characteristics of hydrogen production from waste activated sludge were investigated using separation membrane acid fermentation reactor (AR) and photosynthetic reactor (PR). The AR used submerged and external separation membranes and it was followed by the PR. The COD removal efficiencies in the AR with submerged and external separation membrane were about 65% and 40%, respectively. More VFA was produced in the AR with external separation membrane than AR with submerged separation membrane. Hydrogen was produced in the PR but not in the AR and hydrogen productions in the PR connected with Submerged membrane AR and external membrane AR were about 50.1 and 160.5 ml H-2/g T-VFA, respectively. (c) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.