Hydrogen-enrichment has been proposed as a useful method to overcome drawbacks (local flame extinction, combustion instabilities, lower power Output. etc.) associated to turbulent premixed combustion of natural gas in both stationary and mobile systems For the safe use of hydrogen-enriched hydrocarbon fuels, explosion data are needed. In this work, a comparative experimental study of the explosion behavior of stoichiometric hydrogen-enriched methane/air (with 10% of hydrogen molar content in the fuel) and pure methane/air mixtures is presented. Tests were carried out in a 5 1 closed cylindrical vessel at different initial pressures (1, 3 and 6 bar), and starting from both quiescent and turbulent conditions. Results allow quantifying the combined effects of hydrogen substitution to methane, pressure and turbulence on maximum pressure, maximum rate of pressure rise. burning velocity and Markstein lengths. (C) 2009 Elsevier Ltd. All rights reserved.