In this study, environmental impact analyses and comparisons of various hydrogen production methods are presented. The methods considered are categorized on the basis of various energy sources such as renewables and fossil fuels. For the fossil fuels based hydrogen production, steam methane reforming (SMR) of natural gas is studied. Renewable based hydrogen production includes electrolysis using sodium chlorine cycle. Electrolytic hydrogen production is also compared using different types of cells, such as the membrane, diaphragm and mercury. Wind and solar based electricity is also used in electrolytic hydrogen production. The environmental impacts results of the hydrogen production processes indicate that SMR of natural gas has the highest environmental impacts in terms of abiotic depletion, global warming potential, and other impact categories. The abiotic depletion for SMR is found to be 0.131 kg Sb eq. which is the highest among all methods including renewable based hydrogen production. The second highest abiotic depletion value comes from the electrolysis, using the mercury cell, which is 0.00786 kg Sb eq. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.