This paper discusses the decomposition processes of polymer thin films coated on silicon (Si) substrates by hydrogen radicals generated from H-2 on hot-wire catalyst surfaces. N-2 buffer was used to relax the translational motion of hydrogen radicals. It is shown that H atoms react to polymer films under thermal equilibrium conditions when the total pressure is 21.3 Pa and the distance between the catalyst and the substrate is 100mm. Polymers with benzene ring such as phenol resin, polystyrene, poly(vinylphenol), and poly(alpha-methylstyrene) exhibited both low removal rate and high activation energy of decomposition compared to those polymers without benzene ring such as poly(methylmethacrylate) and poly(isobutylene). We concluded that benzene ring with CC bond and resonance structure is resistant to decomposition by hydrogen radicals. (C) 2014 Elsevier B.V. All rights reserved.