Smooth hydrocarbon films formed on the vacuum chamber walls in tokamaks under the erosion of graphite elements during deuterium plasma discharges are the main accumulators of hydrogen isotopes in carbon matrices. Therefore, they can be considered as a promising material for hydrogen storage applications. In the present work, such hydrocarbon CD x films (x ∼ 0.5) produced in T-10 tokamak (NRC Kurchatov Institute, Russia) were studied using scanning electron microscopy (SEM), NEXAFS and EXAFS spectroscopies together with thermal desorption (TD) for the films' characterization and estimation of their hydrogen storage capacity. The C 1s X-ray absorption spectra of the CD x films were recorded for the first time using the BESSY II storage ring facility (Germany). The obtained NEXAFS spectra were found typical for CK-spectra of sp 3 + sp 2 hydrocarbon systems with a high H/C ratio. The role of Fe impurities from the tokamak chamber walls was elucidated as a catalytic effect "facilitating" the thermal desorption of hydrogen (deuterium) from CD x films. The Fe K-edge spectra allowed to confirm a fractal (self-affined) structure of CD x films, with a minimal sp 2 fractal aggregate ∼2-3 nm, and formation of 3D carbon sp 3 + sp 2 network, accumulated a large number of H-isotopes and C x H y hydrocarbons. It was found that the H storage and thermal desorption properties of the CD x films can be improved by their inherent Fe impurities, capable to reduce the barrier of TD and to increase the H/C storage capacity by several times even at room temperature.