Short contact time catalytic partial oxidation (SCT-CPO) of natural gas is a promising technology for syngas production, representing an appealing alternative to existing processes. The high conversion and selectivity observed since the earlier works in this field can make this process attractive. Moreover, the SCT-CPO reactors can be autothermally operated and the possibility to use air as oxidant appears a feasible route to reduce syngas production costs: these two issues make possible the use of a SCT-CPO reactor as the reformer of a fuel processor for H-2 production for fuel cells. The present work refers to an experimental study of syngas production from CH4 and O-2 via a SCT-CPO reactor made of a fixed bed of Rh/alpha Al2O3 spheres. The main obtained results are: (i) an increase in GHSV produces an enhancement of transport rates and this in turn determines an improvement in CH4 conversion, despite the reduction in residence time; (ii) the catalyst pellets get hotter than the gas phase thus favouring the H-2 and CO production: syngas formation is in fact both thermodynamically and kinetically promoted at high temperatures; (iii) a similar improvement of conversion was obtained with a reduction of the catalyst particle size, thanks once again to an increase in the heat transport and a higher geometrical surface area of the catalyst itself. By a slight increase of the O-2 fed to the reactor, H-2 and CO yields can be maximised and a complete CH4 conversion achieved. (c) 2006 Elsevier B.V. All fights reserved.