Data are presented for the refractive index of Irtran 2, a hot-pressed microcrystalline compact of ZnS, made by the Eastman Kodak Company, from 1 microm to 15 microm and from 93 K to 283 K. The values range from 2.35 at both high temperatures and short wavelengths to 2.12 at the opposite extremes. The average value of dn/dT is about 4 x 10(-5) K(-1) at 104 K for all wavelengths, with a value of 2 x 10(-7) K(-2) for the temperature variation of dn/dT.