It was demonstrated that polymeric carbon formed during the preparation of Mo2C/SiO2 from MoO3/SiO2, which is located on the support. The adsorptions of CO and CH3 on silica-supported MoO3 and Mo2C catalysts was investigated by FTIR. While CO did not adsorb strongly on MoO3/SiO2, stable bands at 2089 and 2032 cm(-1) on Mo2C/SiO2 were detected in CO dsorption. which can be regarded as an indication for noble metal-like character of supported Mo2C. CH3(a) on MoO3/SiO2 (2920 cm(-1)) proved to be more stable, than CH3(a) on Mo2C/SiO2 (2924 cm(-1)). In the surface reaction of CH3(a) on Mo2C supported on silica ethylene formation was detected by mass spectrometric analysis. Ethylene did not form on SiO2 and on MoO3/Sio(2). (C) 2003 Elsevier B.V. All rights reserved.