The present invention relates to double-base solid propellant mixtures whose burning characteristic is regulated by the addition of certain moderators such that the burn rates obtained are achieved independently of the temperature and pressure during the burn. This regulation is accomplished by the addition of a mixture of carbon black and cellulose acetate. The weight ratio of carbon black to cellulose acetate in this mixture is between 1:0.5 and 1:10. Depending on the composition of the solid propellant, the combustion of the rocket fuel can be regulated by regulating this mixture within the stated limits such that it takes place independently of temperature and pressure. The amount of the carbon black and cellulose acetate mixture present in the fuel can vary between 0.2 and 6% by weight; the carbon black is contained in the propellants of the invention in amounts between 0.05 and 1.0% by weight. The charges contain as the energy-supplying component a mixture of cellulose nitrate and nitroglycerin, as well as known additives to facilitate working and increase the rate of burn. The effect in accordance with the invention is found also in those propellant charges which additionally contain as energy-supplying component still other known, high-energy substances.