The aim of this work is to investigate the corrosion protection of copper using self-assembled monolayers of stearic acid in 3% NaCl solution over 24 days of measurement. The test specimens were treated with stearic acid, with some of the specimens being pre-oxidized in NaOH solution or in hot water. The measurements were taken by alternating current (AC) and direct current (DC) electrochemical methods. From the DC techniques, the Tafel extrapolation method and the linear polarization method were applied, while the AC technique used was electrochemical impedance spectroscopy. Goniometry and Fourier Transform Infrared spectrometry (FTIR) were used to test the surface characteristics of the sample. The results of the measurements showed that the sample treated with stearic acid, c(SK)=10^-3 M showed the lowest protection of copper, followed by the sample oxidized in hot water, since the polarization resistance of these samples decreased after the second day of the measurement. Samples treated with c(SK)=10^-2 M with or without additional oxidation in u hydroxide showed better protection. The longest lasting protection was obtained for a sample treated with the solution with higher concentration of stearic acid, without prior oxidation in NaOH solution or hot water.