This study evaluates the combined effect of ultrasound and microwave energy assistance, together with different concentrations of the cationic surfactant CTAB, on the synthesis and stabilization of gold nanoparticles (AuNPs) obtained by chemical reduction. Characterization techniques such as STEM, DLS, UV-Vis spectroscopy, thermogravimetric analysis, zeta potential, and FTIR were employed to investigate morphology, colloidal stability, and surface functionalization. The results showed that microwave assistance with 0.05 M CTAB favors the formation of smaller and more homogeneous AuNPs, with an organized and stable surface coverage, as evidenced by the higher zeta potential (+35 mV), the reduced particle size observed by STEM (∼9 nm), and the presence of an extensive micellar layer detected by DLS the thickness of the CTAB layer: 68-9=59 nm. FTIR and TGA confirmed the effective adsorption of CTAB onto the nanoparticle surface, as indicated by the disappearance of bands associated with the quaternary ammonium group and the enhanced thermal stability of the AuNP-CTAB system compared to the free surfactant. These findings demonstrate that the synergistic optimization of the energy source and surfactant concentration enables control over AuNP morphology and surface functionalization, with relevant implications for applications in biosensors, catalysis, and stable colloidal systems.