We report on the suppression of FeLi antisite defects in LiFe(PO4)1−xF3x with 0 ⩽ x ⩽ 0.4 prepared by sol–gel and hydrothermal methods. Evidence for a systematic suppression of antisite defects upon fluorine doping in LiFePO4 is inferred from Fourier transform infrared spectra, wherein a noticeable red shift in the symmetric P–O stretching vibrational mode of (PO4)3− polyanion from 970 to 957 cm−1 was observed. We report detailed structural and compositional studies of LiFe(PO4)1−xF3x, and discuss the implications for the performance of LiFePO4 cathodes in lithium ion batteries.