Etherification of a typical C-6 olefin, 2,3-dimethyl-1-butene, with methanol was investigated over commercial ion-exchange resins and several clay-based acid solids prepared by sulfuric acid treatment or impregnation of sulfated zirconia and Nafion. The commercial resin catalyst Amberlyst 15 is effective but nonselective to ether production, while Nafion is less active. For two clay systems, montmorillonite-based catalysts generally exhibit higher activities than bentonite and MT-H2SO4 will be a highly active and selective catalyst than the supported sulfated zirconia and Nafion.