The Spaceborne Infrared Sounder for Geosynchronous Earth Orbit (SIRAS-G) represents a new approach to infrared imaging spectrometry suitable for Earth observation from geosynchronous orbit. SIRAS-G is currently being developed under NASA’s Instrument Incubator Program (IIP-4). SIRAS-G is an instrument concept with lower mass and power requirements than heritage instruments that offers enhanced capabilities for measuring atmospheric temperature, water vapor, and trace gas column abundances in a compact package. The flight instrument concept measures infrared radiation in 2048 spectral channels with a nominal spectral resolution (λ/Δλ) of 1400. The system employs wide field-of-view hyperspectral infrared optical system that splits incoming radiation to four separate grating spectrometer channels. Combined with large 2-D focal planes, this system provides simultaneous spectral and high-resolution spatial imaging. In 1999, the SIRAS team built and tested the SIRAS LWIR Spectrometer (12.0 - 15.4μm) under NASA’s Instrument Incubator Program (IIP-1). SIRAS-G builds on this experience with a goal of producing a laboratory demonstration instrument including the telescope, a single spectrometer channel, focal plane and active cooling subsystem. In this paper, we describe the on-going development of this laboratory demonstration instrument, including design, performance requirement predictions, and potential future scientific instrument applications.