The application possibilities of austenitic stainless steels in high friction, abrasion and sliding wear conditions are limited by their inadequate hardness and tribological characteristics. In order to improve these properties, thermochemical treatment of their surface by plasma nitriding is suitable. This article is focused on corrosion resistance of the conventionally plasma nitrided AISI 304 stainless steel (530 °C, 24 hours) in 0.05 M and 0.5 M sodium chloride solutions at room temperature (20 ± 3 °C), tested by potentiodynamic polarization and electrochemical impedance spectroscopy. The optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy are used for the nitrided layer characterization. The experiment results point to a significant reduction in corrosion resistance after performed plasma nitriding even in a solution with a very low chloride concentration (0.05 mol/L).