The addition of interstitial elements in metals, as titanium and its alloys, causes alterations in their mechanical properties, making them either softer or harder, for example. The internal friction measurements have been frequently used in order to verify the behavior of these interstitials atoms in metallic alloys. This paper presents the oxygen diffusion in Ti-10Mo alloy by the analysis of the mechanical relaxation spectra, in the temperature range of 350-600 K. The relaxation structure obtained was analyzed by means of the frequency dependence of the peak temperature and by using a simple mathematical treatment of the relaxation structure and the Arrhenius law.