A new higher Co-oxide has been synthesized. Its features are presented by means of IR-spectroscopy, X-ray analysis, XPS-spectroscopy, EPR, magnetic measurements and chemical analysis in a separate paper by the present authors. On the grounds of the obtained results the following formula, determining the content of the higher Go-oxide, has been put forward. Co1-x+2Cox+4Oy(OH)(y) . mH(2)O, with the Co-ions being in their highest oxidation degrees (i.e. +4) and in an octahedral position. The synthesized Go-oxide system can be utilized as an active phase of a low-temperature catalyst as well as a strong oxidant for a complete oxidation in liquid and gas mediums. The present paper also studies the thermal stability of the synthesized Co-oxide system by means of thermal analysis, IR-spectroscopy, X-ray and chemical analysis. The results show that both the freshly obtained higher Co-oxide and the thermally treated (up to 250 degrees C) samples maintain their composition, structure and activity in the oxidation processes. Heated at temperature above 250 degrees C, the Co-oxide system undergoes changes in its composition and structure, turning it into a cobaltite with a spinel structure. This is the reason for the sharp decrease of the activity of the studied system in the oxidation processes.