Development of a mild (35 degrees C, no Breasted acids) tandem Wacker oxidation dehydrogenation of terminal olefins was accomplished using palladium(II) and hypervalent iodine co-catalysis. The reaction affords linear aryl and alkyl alpha,beta-unsaturated ketones directly from readily available terminal olefins in good yields (average 75% per step) with excellent functional group tolerance and chemo- and stereo-selectivities. The hypervalent iodine co-catalyst was found to be critical for dehydrogenation but was not effective as a stoichiometic oxidant.