Gas generating compositions or propellants are provided which comprise a fuel and a novel oxidizer therefor comprising an inorganic compound having a poly(nitrito) transition metal complex anion. The inorganic oxidant compounds are generically represented by the formula:M.sub.x.sup.1 M.sub.y.sup.2 (NO.sub.2).sub.zwherein (1) M.sup.1 is a metal selected from the (a) Group IA alkali metals, (b) Group IIA alkaline earth metals, preferably strontium, (c) Group IB metals, preferably copper, and (d) Group IIB metals, preferably zinc, of the Periodic Table, (2) M.sup.2 is a metal selected from the transition metals of Groups IVA-IIB of the Periodic Table, (3) x=1, 2, 3, or 4; y=1 or 2, and z=4 or 6 as determined by the required stoichiometry of the metals of the complex, and (4) the M.sup.1 and M.sup.2 metals selected are different metals. M.sup.1 is preferably the Group IA alkali metals, more preferably sodium and potassium, and most preferably potassium. M.sup.2 is preferably the Group VIIIA, IB and IIB metals, more preferably cobalt, copper and zinc from the respective Groups, and most preferably cobalt. The most preferred oxidant is potassium hexanitrocobaltate, K.sub.3 Co(NO.sub.2).sub.6. Preferred alternate oxidizers are potassium tetranitrocuprate, K.sub.2 Cu(NO.sub.2).sub.4, and potassium tetranitrozincate, K.sub.2 Zn(NO.sub.2).sub.4.