Nowadays aseptic loosening is the most common cause of orthopaedic implant failure. Some of its reasons have already been described up to now; however, others remain still hypothetical. Besides the inflammatory response to wear particles originating at different sources, the role of reactive oxygen species as products of cellular reactions and/or as a result of the process of corrosion of an implant leading to implant failure has recently been discussed too. In the present study, we used a galvanostatic polarization to simulate the cathodic partial reaction of the corrosion process at a titanium alloy surface. With respect to cells occurring at the interface of a metal implant, the behaviour of osteoblasts and monocytes/macrophages was investigated. It has been found that cathodic polarization of Ti6Al4V induces an increase in the level of intracellular reactive oxygen species as well as suppressing the metabolic activity of cells in a dose-dependent manner. This is in agreement with the results obtained with cells after external addition of hydrogen peroxide as another kind of oxidative stress. In both approaches, monocytes/macrophages show a higher tolerance to oxidative stress than osteoblasts. It could be concluded that the electrochemical setup developed induced intracellular changes occurring during oxidative stress and it could be used for future detailed analysis of the consequences of corrosion processes for cellular reactions.