Gold nanoparticles (GNPs) were conjugated with gallic acid (GA) at various concentrations between 30 and150 μM and characterized using transmission electron microscopy (TEM) and UV–Vis spectroscopy (UV-VIS).The anticancer activities of the gallic acid-stabilized gold nanoparticles against well-differentiated (M213) andmoderately differentiated (M214) adenocarcinomas were then determined using a neutral red assay. The GAmechanism of action was evaluated using Fourier transform infrared (FTIR) microspectroscopy. Distinctivefeatures of the FTIR spectra between the control and GA-treated cells were confirmed by principal componentanalysis (PCA). The surface plasmon resonance spectra of the GNPs had a maximum absorption at 520 nm,whereas GNPs-GA shifted the maximum absorption values. In an in vitro study, the complexed GNPs-GA hadan increased ability to inhibit the proliferation of cancer cells that was statistically signiﬁcant (P<0.0001) in bothM213 and M214 cells compared to GA alone, indicating that the anticancer activity of GA can be improved byconjugation with GNPs. Moreover, PCA revealed that exposure of the tested cells to GA resulted in significantchanges in their cell membrane lipids and fatty acids, which may enhance the efficacy of this anticancer activityregarding apoptosis pathways.