To model the industrial relevant dehydration process of tert-butyl alcohol in sulfuric acid, a new mechanistic reaction scheme is applied that accounts for a parallel reaction path via di-tert-butyl ether (DTBE). Based on the quasi-steady-state approximation concerning intermediates, a mathematical model is developed that incorporates the acidity of the solvent. Model validation is performed by means of experimental data obtained from stationary continuously stirred tank reactor (CSTR) measurements at different temperatures under reaction conditions that exclude the formation of oligomers. It is shown how numerical simulations, combining this mathematical model with experimental correlations, allow for maximization of isobutene yield in a batch reactor in the regime where the formation of oligomers is avoided.