The nascent vibrational energy distributions of the HF† formed in the reactions of a series of partially fluorinated alkanes (RFH; RF = CH2F, CHF2, CF3, C2F5, C3F7, and C7F15) with electronically excited oxygen atoms O(21D2) have been determined by measuring the appearance times of stimulated emissions from various vibration–rotation transitions in a grating‐tuned optical cavity. The vibrational energy contents of the HF formed in these reactions were found to be considerably greater than statistically expected. These reactions are believed to occur via vibrationally excited short‐lived α;‐fluorinated alcohols (RFOH†), formed by insertion of the O(21D2) atoms into CH bonds. The observation of nonstatistical energy partitioning in the above reactions is in clear contrast to the result obtained from the O(21D2) + CF3CH3 reaction that produces the β‐fluorinated alcohol CF3CH2OH, from which the HF product carries a near statistical vibrational energy distribution. A mechanism for HF† formation in these very exothermic reactions is presented.