This work presents a study of the total chloride contents in concrete and the corrosion process by testing electrical resistivity and half-cell potential of concrete samples. The analysis was based on an experimental investigation of the samples with the time of immersion in 3.5% mass NaCl aqueous solution at room temperature for 18 months, according to European Standards. For this study, different mixtures of concrete were prepared by adding two types of superplasticizers and calcium nitrate inhibitor, in different concentrations. The results of the Cl- ions test showed that all the samples, after an immersion testing period of six months, contained high concentrations of Cl- ions. Samples C4 with 3% calcium nitrate inhibitor and Oxydtron superplasticizer as well as C3 with 3% calcium nitrate inhibitor and Mapei Dynamon SR 31 superplasticizer, showed good resistance to corrosion, in the tested environment. It was also proved by the results of several sets of measurements of the electrical resistivity and half-cell potentials carried on the concrete test samples, to the end of the 18 months testing period.