An improved catalytic dehydrogenation process which process comprises contacting an alkane or alkyl aromatic feedstream with a dehydrogenation catalyst under catalytic conditions in an up-flow fluidized reactor, wherein the fluidized reactor comprises one or more reactors, which catalytic conditions include a temperature within a range of from 500 to 800° C., a weight hourly space velocity within a range of from 0.1 to 1000, a gas residence time within a range of from 0.1 to 10 seconds, and, subsequent to the fluidized reactor, effecting separation of entrained catalyst from reactor effluent by use of a cyclonic separation system, wherein the improvement comprises interposing a cooling means between an up-flow fluidized reactor and the cyclonic separation system to substantially halt thermal reactions, thereby effectively increasing overall molar selectivity to alkene product is provided.