Abstract A new one-step synthesis of 3-hydroxymethylbenzofuran, based on intramolecular cyclization of 2-(methoxymethyl)-2-(2′-methoxymethyl-4′-methylphenyl)-butanone 1 under diluted hydrochloric acid in THF, was developed. The mechanism for this process was investigated via chemical equilibrium shift of tautomer in acidic conditions. The applicability of this new method was studied further in this paper.