Rate constants for gas phase reaction of NO3 radicals with the aldehydes hexanal, heptanal, octanal and nonanal have been determined at room temperature of 298 ± 2K and at atmospheric pressure of 1010 ± 5mbar. Relative rate method was used to perform the experiments. One set of measurements was performed in a 153L borosilicate glass chamber with Fourier Transform Infrared (FTIR) spectroscopy as the analytical method. The other set was performed in a 100L Teflon bag where Solid Phase Micro Extraction (SPME) was used for sampling and Gas Chromatography (GC) with Flame Ionization Detector (FID) for the analysis. Using propene and/or butanal as the reference compounds, the rate coefficients of (1.6 ± 0.1)*10-14, (2.0 ± 0.3)*10-14, (1.9 ± 0.2)*10-14, and (2.1 ± 0.8)*10-14 (in units of cm3 molecule-1 s-1) were obtained for hexanal, heptanal, octanal, and nonanal, respectively. The obtained rate coefficient for hexanal is in good agreement with values from previous works.