We propose a novel superlattice (SL) InAsySb1−y)/InxTl1−xSb lattice matched to InSb for a potential application as an infrared detector material in the 8–12 μm wavelength range. We report on the results of energy band calculations for this SL using the modified Kronig-Penney model. Our preliminary calculations indicate that InAs0.07Sb0.93/In0.93Tl0.07Sb would exhibit a type-I SL with conduction band offset of 34 meV and valence band offset of 53 meV at 0K. Due to the lack of accurate information on material parameters, namely, energy offsets and effective masses of InTlSb, these were estimated by comparison with the behavior of HgCdTe system. The theory predicts three heavy hole subbands and one partially confined electron in the 30Å InAs0.07Sb0.93/100Å In0.93Tl0.07Sb SL. The band gap of the SL was computed to be 0.127 eV (9.7 μm). It is expected that this SL will allow improvements in the InTlSb epilayers’ structural quality as it will be sandwiched between higher quality zincblende InAsSb layers.