A tertiary butyl alcohol charge stock contaminated with from about 0.5 to about 2 wt. % of corrosive oxygen-containing impurities, including peroxides and formates, is passed through an oxygenates decomposition reactor containing a bed of a basic zeolite catalyst to decompose the peroxides and oxygen-containing impurities, including peroxides and formates, and to dehydrate a portion of the tertiary butyl alcohol to form isobutylene and water to form a substantially less-corrosive tertiary butyl alcohol feedstock that is substantially free from oxygen-containing impurities, including formates that is suitable for reaction with methanol in a methyl tertiary butyl ether etherification reactor to form a methyl tertiary butyl ether etherification reaction product from which methyl tertiary butyl ether can be recovered.