An efficient method for the acylation and formylation of alcohols and phenols by using an acylating/formylating agent (acetic anhydride and formic acid) in the presence of a catalytic amount of N,N-dibromo-N,N–1,2-ethanediylbis(benzene sulfonamide) under mild and solvent-free conditions at room temperature in good to excellent yields is described. The use of protic acids and metal Lewis acids is avoided.