Excellent stability on the electrical characteristics of graphene field effect transistors in an air ambient is achieved by inserting an amorphous fluoropolymer between the graphene channel and SiO(2) gate dielectric. The interface engineering exploits the highly water repellent property of the fluoropolymer stemming from high hydrophobicity and low moisture permeation, and results in negligible hole doping of graphene from absorption of water molecules. In addition, the graphene field effect transistors with the fluoropolymer/SiO(2) gate dielectric shows superior performances including negligible V(Dirac) hysteresis and highly stable carrier mobility, which are important characteristics for analog rf device applications. (C) 2011 American Institute of Physics. [doi:10.1063/1.3578396]