Self-assembled nano film of 4-amino-3-(octadecylthio)-6-methyl-1,2,4-triazinone (AOTMT) has been developed on fresh copper surface at ambient temperature. The optimum conditions for the formation of AOTMT nano film have been established through electrochemical impedance and quartz crystal nanobalance studies. The AOTMT film on copper surface is characterized by contact angle measurement, X-ray photoelectron spectroscopy (XPS), reflection absorption FTIR spectroscopy and atomic force microscopy. It is inferred that the formation of AOTMT film is through chemisorption of AOTMT on copper surface due to the nitrogen and subsequent complex formation between AOTMT and Cu+ ions. Corrosion protection ability of AOTMT nano film is evaluated in dilute aqueous HCl environment using impedance, potentiodynamic polarization, cyclic voltammetry (CV), weight-loss and XPS studies. The results show that AOTMT nano film affords excellent corrosion protection to copper in HCl environment. The CV studies show good stability of AOTMT nano film. Potentiodynamic polarization studies reveal that the AOTMT nano film functions as a cathodic inhibitor. The mechanistic aspects of corrosion protection of copper by AOTMT nano film are also discussed.