Monitoring hydrogen production from renewable biomasses suffers from the presence of CO or CO2, even in the amount of traces. Catalytic electrode poisoning is one of the most serious issues when noble metals are involved. We report the engineering of a polymer based sensor device working under limiting current conditions by using the diffusion hole amperometric detection principle. The amount of hydrogen is determined by separating the hydrogen through a Pd barrier and freezing out the CO and CO2. Four different designs were fabricated and studied under CO2 containing H-2 atmosphere up to 80 degrees C. (C) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.