Anaerobic digestion of press mud mixed with water for biohydrogen production was performed in continuous fed UASB bioreactor for 120 days. Experiment was conducted by maintaining constant HRT of 30 h and the volume of biohydrogen evolved daily was monitored. Various parameters like COD, VFA, Alkalinity, EC, Volatile solids, pH with respect to biohydrogen production were monitored at regular interval of time. SBPR was 10.98 ml g(-1) COD reduced d(-1) and 12.77 ml g (1) VS reduced d(-1) on peak yield of biohydrogen. COD reduction was above 70 +/- 7%. Maximum gas yield was on the 78th day to 2240 ml d (1). The aim of the experiment is to study the startup process of UASB reactor for biohydrogen production by anaerobic fermentation of press mud. The inoculum for the process is cow dung and water digested in anaerobic condition for 30 days with municipal sewage sludge. The study explores the viability of biohydrogen production from press mud which is a renewable form of energy to supplement the global energy crisis. (C) 2011 Elsevier Ltd. All rights reserved.