Chloride ingress is one of the major causes of reinforced concrete degradation. Chlorides accelerate the breaking of the protective layer of rebars favoring pitting corrosion; furthermore, corrosion products generate cracks in concrete, which further accelerate chloride ingress, increase porosity and reduce the strength. From a chemical perspective, the presence of chlorides and its diffusion into the reinforced concrete matrix is highly influenced by the content and distribution of aluminates (C 3 A), in the same way, in concretes where ultra-rapid strength development and controlled expansion are required the presence of CA determine the chloride diffusion. This can be explained because chlorides react with aluminates to form Friedel's salts and other compounds. Although these reactions have been widely studied, their electrical changes still require further evaluation and analysis. These experimental works use dielectric spectroscopy (DS), a technique that applying an alternating voltage and measuring phase and magnitude of current can determine the dielectric behavior variation. Also, this technique has shown good potential for measuring chlorides in other materials. Within this context, the main objective of this paper is to present the results of a study of the dielectrical behavior of calcium aluminate (in presence of mayenite and other ferrite compountds) when it interacts with solutions of chloride ions (Cl-) at different concentrations (0-1M) using DS. In addition, the paper includes a structural characterization, by SEM, which provides information about changes in the microstructure and the spatial distribution of chemical elements. The results show that changes in dielectric parameters of CA are proportional to chloride content; in addition, chlorides preferentially interact in those zones where Al, Ca, and O are.