A high-resolution quantum cascade spectrometer was developed to study nitrogen dioxide (NO2) line intensities near 6.2 μm. The spectral region ranging from 1629.7 cm−1 to 1632.5 cm−1, which is suitable for the in situ laser sensing of trace NO2 in the atmosphere, was investigated using a thermoelectrically cooled continuous-wave distributed feed-back quantum cascade laser. Forty-three lines of nitrogen dioxide were experimentally studied within the pressure region ranging between 0 and 90 mbar. The measured intensities were thoroughly compared to the latest HITRAN16 database, a good agreement within ±3% was obtained for most of the established lines.