The paper presents the results of titanium oxide-layers stability and bioactivity evaluation in synthetic body fluids (SBF). The samples are achieved by titanium and its TA6V4 alloy anodic oxidation and heat treatment in air. The cyclic voltammetry and the transmission electronic microscopy investigations show that simply anodically oxidized samples posses a thin, nanostructured, stable oxide-layer. The electrochemical reactivity of the samples is unfavorably raised by heat treatment below 600 โข C, when the presence of detrimental anatase in the layers is evidenced by X-ray diffraction analysis. The same analysis shows that the favorable rutile appears in the oxide-layer at 600 โข C, but it predominates or even becomes exclusive after the heat treatment at 770 โข C. This thermochemical treatment and the resulted crystalline nanostructures ensure an increase of the interface stability and biocompatibility characteristics for the oxide-layers achieved by following an anodic oxidation process, both on titanium and its alloy.