Biological methane production is a more environmentally friendly technology for carbon dioxide reduction than physical and chemical methods. Carbon dioxide can be reduced biologically to methane with hydrogen as the reducing agent under anaerobic conditions. In this study, carbon dioxide discharged from the electronics industry was reduced biologically to methane using the hydrogen produced from electrochemical wastewater treatment. Electrocoagulation technology was applied to treat industrial wastewater and obtain hydrogen without oxygen production. On mixing and injecting the hydrogen and carbon dioxide that were emitted from the facility into an anaerobic reactor, the methane content that was discharged from the anaerobic reactor and the reduction rate of carbon dioxide were 92% and 98%, respectively. This technology, combined with electrocoagulation and biological reaction, reduces carbon dioxide levels and produces methane. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.