The thermal stability of antiepileptic drug phenytoin was investigated on its encapsulation in titania matrix. It was shown that the drug is stable up to 150 degrees C, even though phenytoin melting point was previously reported to be much higher. The mechanism of phenytoin decomposition is suggested and confirmed by the experiment on heating to higher temperatures. The influence of thermal treatment on physicochemical parameters of the matrix was studied. Quite different drug release kinetics were obtained in vitro and discussed in terms of temperature treatment influence and interplay of parameters of the matrix.