We present a conceptual design for an innovative infrared cross-dispersed spectrograph for the NASA Infrared Telescope Facility (IRTF) at Mauna Kea. This facility-class instrument will provide a resolving power of up to 80,000 at 1.2-2.5 μm and 67,000 at 3-5 μm with a minimum slit width of 0.25". The instrument employs a silicon immersion grating in order to reduce the size of the instrument. The design incorporates a 2048×2048 infrared array for the spectrograph and an infrared slit viewer. The optical design is optimized for the thermal infrared (2.8-5.5 μm).© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.