Optical properties of RDX, HMX, AP, HTPB/IPDI and a catalyzed NO/NG propellant (N5) were obtained from 2.5 mu m to 18 mu m using FTIR transmission spectrometry. Scattering-corrected KBr pellet methodology was used for the crystalline materials. Absorption index (k) was measured directly and refractive index (n) was deduced using dispersion theory. At 10.600 mu m the absorption coefficients were AP, 190 cm(-1) (240 cm(-1) at 10.6036 mu m); HTPB/IPDI, 360 cm(-1); N5, 510 cm(-1); RDX, 2800 cm(-1); and Hh LX, 5670 cm(-1).