Major works by Leon Koj deal with the issues of semiotics, logics, philosophy of language, philosophy of mind and ethics. Many of them refer to aspects of communication, however, this is not the main subject of his considerations. These references relate to the problems of satisfying: 1. the logical criteria, 2. the methodological criteria, 3. the ethical criteria, 4. the semiotic criteria. This article is dedicated to defining the semiotic criteria. It briefly covers basic semiotic notions present in Koj’s works. On the basis of Koj’s assumptions the concept of semiotics conditions for the realisation and functions of the communication process is defined.