A combined near-infrared and mid-infrared laser-based absorption sensor is developed for simultaneous measurements of N2O, CO, NO and gas temperature for a 1-Newton ADN monopropellant thruster. ADN monopropellant represents a new generation of green propellant for spacecraft propulsion and goes with developing ADN based thruster. An optimization design for an ADN based thruster with catalytic bed length of 14mm is studied in this paper. Both steady-state firing and pulse-mode firing for the ADN based thruster operation are conducted over feed-pressure range of 5-12 bar at ignition temperature of 200掳C. Scanned-wavelength direct absorption is utilized to measure the multispecies concentration and gas temperature under the firing conditions. Measurements employing the developed laser-based absorption sensor provide an access to characterize the combustion process inside the ADN based thruster. Additional measurements for the combustion pressure are made by using a high-temperature resistant and high frequency pressure sensor. 漏 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.