Both [Pd(hfacac)(2)](2) and [Cu(hfacac)(2)(H2O)(2)] 3 (hfacac = 1,1,1,5,5,5-hexafluoropentane-2,4-dionate) catalyse the oxidation of methane to methyl trifluoroacetate 1 by H2O2 in trifluoroacetic anhydride (TFAA), at temperatures as low as 50 degreesC, under 25-30 atm methane partial pressure, the main by-product being CO2. Under the same conditions, ethane and propane are oxidized to the corresponding trifluoroacetates. The iso-to-normal propyl esters ratio varies markedly (7.2 versus 34) on passing from 2 to 3. (C) 2003 Elsevier Science B.V. All rights reserved.