An improved on-line synthesis of the powerful methylation reagent, [(CH3)-C-11]methyl triflate, 1, is described. By means of a simple and cheap column technique this reagent is synthesized in an overall reaction time of 12 min in reproducible radiochemical yields of 90% (based on (CO2)-C-11), a radiochemical purity of 99% and a mean sp. act. of > 6000 Ci/mmol.