Abstract Real-time combustion and emission control is an ongoing challenge in combustion technology and science. Hence, the scope of the present paper is the investigation of the relationship between the chemiluminescent signal and the CO and NOX emissions. Flame emission spectrometry measurements were carried out to determine the characteristic free radicals of the spectra. For the experiments, a lean premixed liquid fuel burner equipped with an airblast atomizer was used in a test rig at 15 kW combustion power. The following measurement parameters were modified: combustion air flow rate, atomizing pressure, and the vertical alignment of the spectrometer. Furthermore, various half-cone angle quarls were mounted on the burner lip to extend the lean flame blowout stability limit. The CO and NOX emissions and the chemiluminescence intensity ratios of the strongest peaks of OH*, CH*, C2*, HCO*, and CH2O* were evaluated separately at first. Then a correlation analysis of the intensity ratios and the pollutant emission components was carried out. A notable linear correlation was found between both the HCO*/C2* and OH*/C2* intensity ratios and the CO emission in certain parameter combinations.