tert-Amyl methyl ether (2-methoxy-2-methylbutane, TAME) is synthesised in a liquid-phase reaction of methanol (MeOH) and isoamylenes (2-methyl-1-butene (2M1B), and 2-methyl-2-butene (2M2B)). The reaction rates of the formation of TAME were measured in a continuous stirred tank reactor (CSTR) at the temperature range between 323 and 353 K. The molar ratio of methanol to isoamylenes and the concentration of the reagents were varied in the feed. As the alcohol-isoamylene mixture behaves non-ideality, the equilibrium constants and the kinetic analysis was performed in terms of activities using the Wilson method for activity coefficient estimation. In the first stage, the kinetic parameters of the published kinetic models were estimated with the experimental data. In order to describe the interaction of the reaction medium and the catalyst better, the solubility parameter was added to the kinetic models. The best fit was obtained with the model that included the solubility parameter and was based on the Eley-Rideal (ER) type mechanism.