Fluorinated amorphous carbon (a-C : F,H) films were deposited by inductively coupled plasma using CH4 and CF4 gases. Actinometrical optical emission spectroscopy (AOES) was used to determine the relative concentrations of various radicals, CF, CF2 CH, C2, H and F, in the plasma as a function of gas flow ratio R, R= [CH4]/([CH4]+[CF4]). The structural evolution of the films were characterized by Fourier transform infrared transmission (FTIR) spectroscopy. The relationship between the film deposition and the precursor radicals in the plasma was discussed. It was shown that CH radical, as well as CF, CF2, C2 radicals are of the precursors, contributing to a-C : F, H film growth. Actinometrical optical emission spectroscopy (AOES) was used to determine the relative concentrations of various radicals, CF, CF2CH, C2, H and F, in the plasma as a function of gas flow ratio R, R = [CH4] / ([CH4] + [CF4]). The structural evolution of the films were characterized by Fourier transform infrared transmission (FTIR) spectroscopy. between the film deposition and the precursor radicals in the plasma was discussed. It was shown that CH radical, as well as CF, CF2, C2 radicals are of the precursors, contributing to aC: F, H film growth.