In this study, optical emission spectroscopy was used to investigate the advantages of using NH 3 and water with Ar gas plasma. All plasmas in this work were non-thermal plasma with T e higher than T g , especially in N 2 and Ar/NH 3 -H 2 O plasmas, T e , T v , T r and T g were 3.3×10 4 K (ca. 2.5 eV), 7×10 3 K (ca. 0.5 eV), 1×10 3 K, and 3.2×10 2 K, respectively. In the Ar/NH 3 -H 2 O plasma, similar to the Ar/H 2 O plasma, water dissociated readily to form OH and H radicals. On the other hand, in the PTFE surface treatment with Ar/NH 3 -H 2 O plasma, the suppression of NH 3 dissociation may be caused by the increased formation of NH 3 + , which may be a key species in promoting defluorination. Simultaneously, the higher OH radical concentration may increase more the number of polar groups bound to the polymer surface to decrease the WCA and to make PTFE surface super hydrophilic.