An improved process for reacting crude aqueous methanol feedstock with isoolefinic hydrocarbons to produce C₅⁺ methyl isoalkyl ethers, which comprises: contacting the aqueous methanol feedstock with a liquid hydrocarbon extractant rich in C₄⁺ isoalkene under liquid extraction conditions; recovering an aqueous phase containing the major amount of water introduced with the feedstock; recovering an organic extract phase comprising the hydrocarbon extractant and a major amount of methanol introduced in the feedstock; and reacting the extracted methanol and C₄⁺ isoalkene in contact with an acid etherification catalyst under catalytic reaction conditions to produce ether product.