A thermal regeneration process of bone char (BC), used in fluoride adsorption, was investigated in this study. Adsorption experiments and solids characterization by Scanning Electron Microscopy (SEM), X-ray Fluorescence (XRF), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS) and Raman Spectrometry were performed in order to get an insight about the physical and chemical transformations. The results show the evidence that there was diffusion of fluoride ions into bone char particles during thermal regeneration process. In addition, the formation of fluoridated hydroxyapatite is also observed showing that fluoride has been incorporated into the hydroxyapatite structure present in bone char, clarifying the mechanisms of thermal regeneration. In addition, it was observed that the heat (thermal) treatment could increase the degree of crystallinity of bone char. The adsorptive process of fluoride in bone char was fitted to pseudo second order kinetic model and was well represented by Freundlich, Redlich-Peterson and Sips isotherm models, pointing out the prevalence of chemical adsorption and formation of heterogeneous layers on the bone char surface. The results also indicated that the optimum temperature for thermal regeneration was 400 °C.