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Metastable intermolecular composites (MICs) typically use Al as fuel and transition metal oxides as oxidizers, while their reactivities are hindered by the inert Al 2 O 3 passivation layer on the surface of Al particles. Recently, transition metal fluorides have emerged as novel fluorine-containing oxidizers for promoting the reactivity of metal fuels through interfacial fluorination of oxide layer. In this work, nanosized CoF 2 and Co 3 O 4 were prepared through pyrolysis of CoF 2 ·4H 2 O precursor using different calcination conditions. To investigate the function of CoF 2 in reaction and the influence of CoF 2 content on reactive performances, a series of MICs composed of n-Al, Co 3 O 4 , and CoF 2 were prepared through ultrasonic dispersion method. Thermal analysis indicated that Al/CoF 2 composite had significantly higher specific heat release (2.30 kJ/g) than that of Al/Co 3 O 4 composite (1.45 kJ/g), and CoF 2 facilitated the occurrence of exothermic reaction at a relatively lower temperature. AlF 3 was found as main reaction products of Al/CoF 2 at 650 °C, and AlF 3 sublimes at the temperature above 850 °C. Although the pressure output and flame intensity of Al/CoF 2 composite is lower than that of Al/Co 3 O 4 composite, hybrid Al/Co 3 O 4 /CoF 2 composites with 20 %–35 % CoF 2 showed significantly enhanced energetic performances compared with sole Al/Co 3 O 4 , suggesting that CoF 2 can function as an effective reaction modifier. [ABSTRACT FROM AUTHOR]