The methyl cation and CF3+ attack saturated, acyclic ketones to make vibrationally excited adduct ions. Despite their high internal energies and short lifetimes, these adducts undergo deep-seated rearrangements that parallel slower processes in solution. Observed pathways include alkene and alkane expulsions, in addition to (in the case of CF3+) the precedented loss of CF2O + HF. For the vast majority of ketones, the principal charged products are the CF3+ adducts of lighter carbonyl compounds, ions that are not easily prepared by other avenues. Evidence for ion structures comes from collisionally activated unimolecular decomposition and bimolecular ion-molecule reactions. Typical examples are di-n-propyl and diisopropyl ketones (both of which produce CH3CH=OCF3+ as the principal ion-molecule reaction product) and pentamethylacetone (which produces (CH3)(2)C=OCF3+ as virtually the sole ion-molecule reaction product). Isotopic labeling experiments account for mechanisms, and DFT calculations provide a qualitative explanation for the relative abundances of products from unimolecular decompositions of the chemically activated CF3+ adduct ions that are initially formed.