Multicopper oxidases are widely studied enzymes catalyzing the oxygen reduction reaction. Among this family, one class belongs to the copper efflux oxidases (CueOs). They are far less studied in bioelectrochemistry mainly because of the low potential at which they reduce O2. However, the presence of a specific domain rich in methionine residues covering the first copper electron acceptor induces fundamental issues regarding the electron transfer pathway. In addition, as they are involved in copper homeostasis, the understanding of their catalytic mechanism may have important consequences in therapeutic applications. We present here the last findings reported on CueOs based on electrochemical tools. We focus on the proposed roles of the methionine rich domain on the electron transfer process. Especially, copper binding to this domain and consequences on the interfacial electron transfer process appears to be two fundamental aspects to discuss.