The catalytic activity of six different carbons was tested in the solvent-free acetylation reaction of alcohols, phenols, and monosaccharides with acetic anhydride. Three commercial carbons—a basic activated carbon M (Merck KGaA), a moderately basic carbon gel X (Xerolutions S.L.), and an activated carbon N (Norit Netherland B.V.)—were studied. From these commercial carbons, three acidic activated carbons—M-S, X-S, and N-S—were obtained by treatment with sulfuric acid. All six carbons were characterized by means of nitrogen adsorption capacity, porosimetry, elemental organic analysis, X-ray photoelectron spectroscopy (XPS), and point of zero charge (PZC) determination. The experiments carried out showed good catalytic activity, the magnitude of which depended on the type of carbon used. The best catalyst was X-S, which combined high acidity with the largest mesoporous volume. Second in line was the commercial carbon M, which was the most basic. The protocol reported herein encompasses several of the characteristics related to the sustainability of chemical processes, such as the innocuous nature and the affordable cost of the catalytic material, the absence of reaction solvent, and the ease of reaction work-up.