The condensation of beta-naphthol with aromatic aldehydes in the presence of cellulose Sulfuric acid under solvent-free media to afford the corresponding aryl-14H-dibenzo [a.j]xanthenes in excellent yields and short reaction times is described. The reaction work-up is very simple and the catalyst can be easily separated from the reaction mixture and reused several times in subsequent reactions. (C) 2009 Elsevier B.V. All rights reserved.