This work investigates the emission of lean premixed combustion of liquid fuels in a Jet Stirred Reactor (JSR) using experimental and numerical methods.  The experimental work utilizes a probe to measure NOx, CO, CO2 and O2 in the recirculation zone of the JSR. Both chemical reactor networks and computational fluid mechanics are used as numerical tools to better understand the radical lifetimes and the fluid structure of the flow in the JSR.