The problems of improving the safety of various industrial facilities dealing with combustible mixtures are constantly in the center of increased attention. The introduction of chemically active additives into the gas mixture is considered as one of the most effective ways to prevent ignition and explosion. One of the most promising highly effective and, at the same time, environmentally friendly additives is trifluoroiodomethane CF3I. Recently, the effect of CF3I on the ignition of acetylene and methane has been studied; however, combustible gas mixtures encountered in practice are often far from pure gases in composition and contain impurities that can significantly affect the ignition kinetics. In this work, an experimental study of the effect of CF3I on ignition delays behind shock waves of complex combustible mixtures, including mixtures of hydrogen and carbon monoxide (model mixture “synthesis gas”) as well as mixtures of methane with acetylene additives (model mixture “mine gas”) has been carried out. As a result of the experiments, it is shown that in mixtures simulating synthesis gas, CF3I additives lead to a considerable inhibition of ignition, while in “mine gas,” this effect turned out to be insignificant.