The partial oxidation of n-decane to produce H-2, ethylene, and alpha-olefins has been compared over Rh and Pt in autothermal reactors at short contact times. Over Rh it is shown that the addition of an alumina wash coat and small foam pore size give higher H-2 selectivity (> 85%), while the absence of wash coat and larger pore size give more olefins (up to 60%). In contrast, Pt is unsatisfactory for producing either H-2 or olefins because the conversion of both n-decane and O-2 is lower. Pt produces essentially no H-2 (< 0.1% under any conditions). Ignition and autothermal operation over Pt also occur only over a narrow range of composition and flow rate. A catalyst consisting of Pt-Rh gave higher olefin selectivity (89%) than either metal, while producing little H-2. We interpret these results as caused by the high activity of Rh that removes all O-2 early in the catalyst, leaving homogeneous pyrolysis to produce oletins. The lower activity of Pt appears to be caused by its inability to completely dissociate n-decane, leaving fragments on the surface that inhibit reaction and produce a less active surface. (C) 2004 Published by Elsevier Inc.