The electrophilic fluorination of methane with "F+" equivalent N2F+ and NF4+ salts was studied by experiment and theory. Reaction of excess methane with NF4+SbF6- in pyridinium polyhydrogen fluoride solution gave exclusively methyl fluoride. The reaction of N2F+AsF6- and NF4+AsF6- with methane (with 1:2 to 4:1 mole ratio, respectively) in HF solution gave methyl fluoride in 63-92% relative yield with 26-6% methylene fluoride and 2-11% fluoroform with no carbon tetrafluoride formed. In a theoretical study of the CH4 + F+ model reaction stationary points on the potential energy surface were calculated at the QCISD/6-31G*//QCISD/6-31G* + ZPE level. The mechanistic consequences of these reactions are discussed.