The thermal dissociation of several substituted acetophenone molecular ions induced by infrared radiation from a hot wire has been studied in a Fourier transform ion cyclotron resonance spectrometer. The temperature dependence of the dissociation rate constants reveals that the 2'-methylacetophenone molecular ion is characterized by a much higher activation energy for dissociation than other acetophenones. This molecular ion also exhibits a very different behavior with respect to charge-transfer reactions. Unlike molecular ions obtained from other isomeric acetophenones, the 2'-methylacetophenone M+. ion does not promote charge exchange with dimethyl disulfide but does undergo relatively slow electron transfer with ferrocene (IE = 6.74 eV). Ab initio calculations at the MP2/6-31G(d) level predict that the 2-MeC6H4COCH3+. ion (1) can undergo facile tautomerization to the much more stable enol ion 2,2'-(CH2C6H4C+)-C-.(OH)CH3, by a 1,4-hydrogen migration (calculated energy barrier of 20 kJ mol(-1)). The calculated recombination energy of this ion is in good agreement with the observations from the charge-exchange experiments. A full analysis of the potential energy surface suggests that, at low ionizing energies (less than or equal to 11.5 eV), essentially all of the long-lived molecular ions have isomerized to 2. The present example reveals the versatility and some of the advantages of the high-temperature near-blackbody-induced dissociation (hot wire emission) for probing structural problems in ion chemistry.