Transition metal salts such as copper acetates catalyze the reaction of gaseous alkanes with N,N-dialkylmethylamine N-oxides in trifluoroacetic acid (TFA) to afford N,N-dialkylaminomethylated alkanes in good yields. Aminomethylation reaction of propane with trimethylamine N-oxide gave N,N-dimethylisobutylamine as a single regioisomer together with isopropyl trifluoroacetate. Ethane reacts with trimethylamine N-oxide affording N,N-dimethylpropylamine as a sole product. From the reaction of methane, methyl trifluoroacetate was obtained exclusively.