A new quantitative method of estimating the reactivity of aluminum superfine powders for energetic applications has been suggested. The method is based on differential thermal analysis-thermogravimetry (DTA-TG) data analysis in air as oxidizers for measurement first of four reactivity parameters (temperature of intensive oxidation onset, maximum rate of oxidation, degree of conversion of metallic aluminum, and specific heat release). After the comprehensive testing of the powders, the most reactive powder was identified. The special features of the oxidation process for the most reactive samples of aluminum superfine powder, obtained with a wires electrical explosion method, are explained and a theoretical mechanism for a new phenomenon, "pulsed oxidation" of superfine aluminum powder in air, is proposed.