The effect of plasma immersion ion implantation (PIII) treatment on silicone surfaces was investigated by x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR-ATR), and scanning electron microscopy (SEM). Low-energy (at voltages of 4 and 8 kV) and high-fluence (8×10¹⁷ cm^-2) implantation of nitrogen was performed using an inductively coupled plasma source (ICP) at low pressure (~0.03 Pa). The IR absorption spectra showed a significant decomposition in the CH₃, Si-CH₃, and C-F groups of the silicone surface after PIII treatment. The percentage of decomposition was dependent on the implantation energy. The XPS C 1s spectra of the PIII modified surfaces showed an increase in the polar carboxyl (O-C=O) groups and a decrease in the CF₃ groups. PIII treatment shifted the XPS Si 2p peak of silicone to a higher binding energy (around 103.2 eV) and the N 1s peak to lower binding energy (around 398.5 eV). The modified Si 2p, N 1s, and O 1s spectra suggest the formation of SiO_x phases, silicon oxynitrides, and silicon nitrides on the silicone surface after PIII treatment.