Complex formation between aluminium chloride and the ligands 3′,4′-dihydroxyflavone, 3-hydroxyflavone, 5-hydroxyflavone, naringin, 2-hydroxyacetophenone, and methyl protocatechuate has been studied in absolute methanol by u.v. and visible spectroscopy. The stoicheiometry of the complexes favoured under acidic, neutral, or basic conditions at spectroscopic concentrations has been established in each case by the method of molarratios.