Corrosion induced by concrete carbonation can be controlled through the application of electrochemical techniques such as cathodic protection (CP) or electrochemical realkalisation (ER). These methods are generally considered effective in the repair of structures; however, few data are available on the effects of different parameters such as the concrete composition or the exposure conditions. For the temporary technique of ER, moreover, scarce information exists on the durability of the treatment. An experimental research was carried out, aimed at investigating some aspects connected with the application of these techniques in reinforced carbonated concrete. Six different types of concrete mixes were considered. The tests were performed both in a wet and a dry environment. The effect of the pre-corrosion of the reinforcement in concrete was also considered. This article presents results obtained with the technique of ER and discusses the role of the different factors considered. The technique of CP will be discussed in Part II.