In a carbon black manufacturing process a method is provided whereby the off-gas from at least one carbon black manufacturing process is utilized both to lower the temperature of the hot combustion gases and to provide some heat to the hot combustion gases by being burned in the combustion tunnel of a carbon black reactor. A portion of the off-gas is utilized while still holding the total volume of the hot combustion gases substantially constant at a preselected substantially constant temperature to insure a substantially constant quality of carbon black.