n-Butanetliiol-impregnated, micrometric, pristine Ni powder (Ni-C4S) was tested as a catalyst for use in the steam reforming of methane, using X-Ray photoemission spectroscopy (XPS) and mass spectrometry (MS). The catalytic activities of both the pristine Ni and the Ni-C4S powders were measured at 700 degrees C, under conditions that favoured (molar CH4: H2O ratio of 2: 1), and did not favour (molar CH4: H2O ratio of 1:2) formation of surface carbon. The results show that: (a) Ni-C4S demonstrates both high catalytic activity and stability during the 21 h duration test; (b) under conditions favouring the deposition of surface carbon, the Ni-C4S retained both its efficiency and structural integrity, while the catalytic activity of the Ni was reduced by similar to 70% and the catalyst pellets lost their integrity; (c) the amount of deposited carbon in the case of the Ni-C4S catalyst was significantly lower than that observed for the Ni catalyst, in spite of the longer testing duration. It was concluded that the thiols pre-treatment of Ni surfaces, to be subsequently used in the production of catalysts supported SOFC anodes, can considerably increase their "active life span" this being a critical attribute in respect of their eventual commercialization. (C) 2007 Elsevier B.V. All rights reserved.