This study reports an original approach based on the inserting of a cold oxygen plasma treatment as oxidation stage between two pyrolysis processes for the preparation of an activated carbon from vinasse as a waste from the distillation of fermented sugar beet. The effects of pyrolysis temperature and plasma application time on the structural and morphological properties of the prepared carbon materials were investigated by Thermal Gravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FT-IR), Raman Spectroscopy, Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDX) techniques and gas adsorption measurements (BET). The results of the different conditions indicated that the structure properties of the obtained activated carbon were significantly dependent on the pyrolysis temperature. As an optimum condition, the application of oxygen plasma for 5 min between pyrolysis processes at 1000 C-omicron provided an eligible activated carbon with surface area (832.3 m(2)/g) and mainly microporous structure. After preliminary examinations on various dyes, the adsorption performance of the activated carbon with highest surface area was specifically evaluated using methylene blue as a model dye in aqueous solution as functions of various operating parameters. Langmuir adsorption capacity (909.091 mg/g) of the prepared activated carbon toward methylene blue was superior than most of the other adsorbents. (C) 2017 Elsevier B.V. All rights reserved.