The reactions of oxalyl fluoride with electrophiles in the presence of alkalimetalfluoride were carried out. In the reaction with CF3CH2OTf (Tf=CF3SO2) or CH3CH2OTf, the synthesis of di-ether (ROCF2CF2OR) and mono-ether (ROCF2COF) was achieved. The difference of the reactivities between these two compounds was discussed from the result of DFT calculations.