Catalyst poisoning is one of the most significant problems associated with the commercial application of water gas shift catalysts. Conventional site blocking poisoning with sulphur compounds, and particularly by H2S, is common. This work reports the effect of H2S exposure on a Pt-based Water Gas Shift catalyst. A 100 h continuous experiment was made to study the catalyst viability in the presence of 1 ppm H2S. As well as different experimental conditions, temperature, gas hourly space velocity, steam carbon ratio and a concentration of 300 ppm H2S. Gas chromatography (GC) was used in this study to analyse the outlet gas composition through time, and thereby the catalyst performance. The Pt-based catalyst showed to be stable in all the experiments, not losing activity. The maximum conversion obtained was 78% at temperature of 330 degrees C. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.