Three new 5-fluoro-2- methylthio substitutedpyrimidinederivatives have been synthesized and characterized by 1H NMR spectroscopy and Mass spectrometry. Corrosion inhibition characteristics of the synthesized pyrimidinederivatives have been studied on mild steel (MS) in 0.5 M hydrochloric acid solution at various temperatures (303−333 K) using mass loss and electrochemical techniques. The obtained