This paper describes a methodology for the investigation of corrosion of galvanized armor wires used in the construction of wireline logging cables. The methodology involves a detailed characterization of the wires to determine the characteristics of the zinc coating and Zn/Fe alloy zones. Model brine solutions and fully formulated drilling fluids were used to quantify the corrosion of galvanized armor wires in the aqueous fluid system (AFS) using weight-loss analysis and electrochemical techniques. A novel corrosion test protocol was developed to accurately measure both zinc dissolution and surface oxidation of the zinc coating. The degradation of the zinc coating was determined as a function of brine composition, oxygen concentration, pH, and temperature. The effectiveness of a grease coating applied to the wire sample surfaces prior to exposure to the brine was evaluated.