Highly active and stable solid acid catalysts based on ordered mesoporous carbons were synthesized via hard template method and further functionalization with sulfonic (SO3H) groups. Two post-synthetic modification strategies were applied. In the first one, the pristine carbon was modified with concentrated sulfuric acid. The second approach included the reaction of carbon with aryl diazonium cation generated in situ from sulfanilic acid. The morphology, structure, composition, and surface functionalities of the resulting carbons were determined by scanning and transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, N-2 adsorption-desorption measurement, elemental analysis, potentiometric titration, X-ray photoelectron spectroscopy and FT-IR method. The obtained samples were further tested in acetylation of glycerol with acetic acid under various conditions, and were found to efficiently produce acetins, valuable fuel additives. An excellent catalytic activity was shown especially by the SO3H-bearing mesoporous carbon prepared by a facile method with the use of 4-benzenediazonium sulfonate under ambient conditions. Furthermore, very good recycling properties of this catalyst was demonstrated by four consecutive runs. It is supposed that acidic catalytic activity of the synthesized materials can be further extended to other acid-catalyzed reactions.