Electrochemical potential and current noise (EPN, ECN) signals for a rotating disk electrode (RDE) were measured with regard to the electrochemical and electrical contributions. Particular attention was given to the resistance of the electrical connection to the disk because this is considered a source of electrical noise. Electrical noise measurements were obtained in the absence of an electrolyte using a passive load. The noise levels under static and dynamic conditions did not exceed 10 µV for potential and 0.1 µA for current readings. Electrochemical tests for mild steel in 0.1M sodium sulfate (Na²SO⁴) show distinct noise patterns for static and hydrodynamic regimes. It is shown that electrical noise contribution is often negligible when compared to electrochemical noise signals obtained for a corrosion process under uniform attack and laminar flow.