The main objective of this communication is to discuss the engineering of a System of Systems (SoS), including interoperability concept. More precisely, the here presented research focuses on the fundamental requirements to consider in a System of Systems Engineering (SoSE) project and that have to be maintain during the entire life cycle of a SoS. First, the concept of interoperability, according to its definition and its characteristics, is presented. Then, the concept of SoS is presented in the same manner. This leads to introduce and present the possible links between System of Systems and interoperability. These links are (1) clarified and defined, (2) re-expressed to meet requirements’ definition and (3) not related to a given SoS in order to be generic.