We have studied the behavior of phenol and 2-naphthol on (111)Au during electro-oxidation using atomic force microscopy (AFM) and surface Fourier transform infrared spectroscopy (FTIR). As oxidation begins, the AFM shows growth of amorphous features on the (111)Au surface. We observed different modes of nucleation and growth for the two molecules. We associate these features with poison formation as is also inferred from electrochemical measurements. FTIR spectra show an increase in the number and amplitude of absorbence bands as oxidation proceeds, indicating formation of new oxidation products and a thickening film on the (111)Au surface.