Two different approaches to modify the structure and reaction ability of nanocrystalline MgO have been discussed. In the first case, a series of two-component x%MOx-MgO systems (M = Fe, Co and Ni, x = 1-45 wt.%) was synthesized via sol-gel technique. Aqueous solution of inorganic salt precursor was used as a hydrolyzing agent. Samples obtained were characterized by number of physicochemical methods (differential thermal analysis, X-ray diffraction analysis, lowtemperature adsorption, etc.). It was shown that presence of inorganic salt in magnesium hydroxide matrix shifts the temperature of decomposition of latter towards lower values. Structural and textural characteristics of MgO-based oxide systems were found to be strongly affected by the presence of additive and their concentration. Formation of joint phase was observed in the case of cobalt oxide only. Second way of MgO modification was represented by creating a controlled carbon coating over its surface via decomposition of C4H10at 400 °C. The obtained x%C/MgO (x = 1-10 wt.%) samples were shown to possess the improved reaction ability in destruction sorption of CF2Cl2as well as in catalytic dehydrochlorination of 1-chlorobutane in presence of water vapors.