The spectral performance, sensitiveness to ignition stimuli and burning rate of bi-spectral flare formulations based on tetrazole containing fuels, 5-phenyl-1H-tetrazole, 5,5-(1,4-phenylene)bis(1H-tetrazole) and 5-(4-nitro-phenyl)-1H-tetrazole, utilizing potassium perchlorate as the oxidizer, are reported. The formulation based on 5-(4-nitro-phenyl)-1H-tetrazole yielded the highest spectral efficiency in the -band (44.1Jg(-1) sr(-1)). The formulation based on 5-phenyl-1H-tetrazole gave the highest color ratio ((/)=6.8) and was the least sensitive.