This work assesses theoretically the potential of dilute nitride alloys of InNxSb1-x for long-wavelength IR applications. A 10-band k.p approximation modified to account for conduction/valence band coupling is implemented to extract the bandgap as a function of the nitrogen concentration in the alloy and the temperature. The calculations show the possibility to obtain a band closure at similar to 2% of nitrogen for InSbN at 300 K. The absorption coefficient, and its temperature dependence, is then determined using an Elliot-like formalism, predicting stronger absorption properties associated with the enhancement of conduction band effective masses. This enhancement yields over an order of magnitude increase in the non-radiative Auger recombination lifetimes suggesting the potential of InNSb for significantly enhancing detectivity limits and operation temperatures of long-wavelength IR detectors. (c) 2008 Elsevier B.V. All rights reserved.