In the present paper the chemical interaction between an alumina plate and a one-phase NaCl-KCl-K2TiF6 as well as two-phase NaCl-KCl-K2TiF6/Ti system has been studied experimentally at 700 T during 2 hours, as function of K2TiF6 content of the melt. In all experiments the reaction product TiO2 of an exchange reaction has been found at the surface of the alumina plate. Its thickness changes through a maximum point as function of the K2TiF6-content of the melt, as a result of the competition of two processes: the exchange reaction leading to the formation of the TiO2 layer, and its dissolution in the melt.