This work presents investigations into the composition and some properties of nanodispersive powders of aluminum boride prepared by the plasma-recondensation technique. It is shown that, under a strictly determined aluminum : boron ratio in the starting mixture and with the complete observance of technological processing parameters, aluminum boride (n-AB) nanopowders of the required composition and dispersivity can be obtained. SEM investigations of the aluminum boride samples reveal that aluminum boride powders are mixtures of spherical particles of different sizes and a significant agglomeration of the particles is observed. In general, the sizes of particles are varied from several dozens of nanometers up to 500 nm and more. Investigations into the thermal-oxidative activity of synthesized aluminum boride using thermogravimetric and differential thermal analysis show that these compounds are more active towards air than nanodispersive aluminum. The highest rate of oxidation of aluminum borides was observed in the temperature range of 680-700°C.