A new mechanistic reaction scheme of the dehydration of t-butanol in sulfuric acid is proposed which accounts for a parallel reaction path via di-t-butylether. Based on the quasi-steady-state approximation concerning intermediates, a mathematical model is developped that incorporates the acidity of the solvent. Model validation is done by means of experimental data obtained from stationary CSTR-measurements at different temperatures under reaction conditions that exclude the formation of oligomeres. It is shown how numerical simulations, combining this mathematical model with experimental correlations of their generation from literature, allows for maximisation of isobutene yield in batch reactor under avoidance of the formation of oligomeres.