Emanation thermal analysis (ETA) has been used to characterize the thermal behavior of boron-doped diamond polycrystalline film samples prepared by microwave plasma-assisted chemical vapor deposition (MPCVD). The mobility of radon atoms in the diamond film samples was evaluated from the ETA results. From the diffusion structural diagnostics achieved by evaluating the ETA results it followed that the O-plasma treatment of the sample enhanced the mobility of radon atoms in the range of 50-200 degrees C, due to both structure disordering and removal of graphitic carbon. The structure disordering was suggested by the high-resolution XPS results. From the diffusion structural diagnostics data it followed that the annealing of the structure irregularities in the polycrystalline diamond films took place in the range of 250-450 degrees C, the annealing was more intense for the O-plasma-treated sample compared to the H-plasma-treated one, due mostly to the initially greater degree of structure irregularities. (C) 2011 Elsevier B.V. All rights reserved.