It is possible to carry out the partial oxidation of alkanes in reactors with residence times less than 10@super -3@ sec above atmospheric pressure and obtain almost complete conversions with high selectivities to products such as H@sub 2@ and CO, olefins, and oxygenated hydrocarbons. These processes involve extremely large temperature and concentration gradients (10@super 6@ K/sec and 10@super 4@ atm/sec), and at temperatures above 1300K where adsorption lifetimes are typically 10@super -9@ sec. For the oxidation of ethane to ethylene, we can obtain 85% selectivity to ethylene with less than 5% CO and CO@sub 2@, even though at equilibrium CO should be the dominant product. These reactions occur on a PtSn catalyst surface which consists of ~10 µm single crystal particles exposing large facets. EDX and XRD of these catalysts show that they consist entirely of intermetallic PtSn compounds with no free Pt phases. This is accomplished by adding large amounts of H@sub 2@ in a ratio of H@sub 2@/O@sub 2@=2. With this feed, the surface reaction forming H@sub 2@O occurs within the first 100 µsec on the first mm of catalyst, while minimizing ethane oxidation. This consumes all O@sub 2@ leaving ethane dehydrogenation which generates as much H@sub 2@ as is fed to the reactor. At 1300K with 10@super -9@ sec adsorption times and very high reactive fluxes, these processes deviate considerably from conventional catalytic reaction conditions, and these processes may involve partially equilibrated internal states of molecules. Implications of nonequilibrium reaction dynamics at extreme these conditions will be considered.