Carbon-based solid acid (CSA) was successfully prepared using phenolic residue as starting material. The characterization results indicate that such solid acid catalyst mainly consists of four building blocks: the condensed aromatic carbon sheets, the active groups (including -SO3H, -COOH and phenolic OH), the side chains (including -CH3 and -OCH3) and the bridge linkages (including -O-, -CH2-, -CH2-CH2-, and -OCH2-) acting as the intermediates between aromatic clusters. Most of these building blocks, except for the -SO3H, could be derived from the corresponding part of the phenolic residue. Aliphatic side chains have been demonstrated to greatly improve the sulfonation activity of carbon precursor and promote the catalytic performance in cellulose hydrolysis, and the carbon-based catalyst sulfonated for just 1 h could exhibit almost similar catalytic activity compared with the catalyst sulfonated for a longer time. However, their hydrophobicity and steric hindrance reduced the utilization efficiency of the sulfonic acid groups to a certain extent. (C) 2013 Elsevier Ltd. All rights reserved.