There is a lack of attention to the practical implementation by libraries of citizen science projects, science communication and popularization of open science, including outside the academic environment. This situation is due to their relatively recent appearance in the field of researchers’ attention, as well as to the insufficient formation of the necessary competencies among librarians (especially those who graduated before the introduction of competency-based bachelor’s degree programmes).The study aims to address two objectives: 1) identification of specific competences required for a popularizer of open science in a library; 2) development of a structural and functional model of formation of such competences in vocational training.The competences necessary for a librarian-bibliographer — popularizer of open science are proposed. They are related to project and communicative activities, social partnership, support of scientific research, formation and presentation of content, including media content. The methods of mass work are important, as well as the organization of multifunctional library space, its zoning and navigation in order to ensure the comfort of users needed for the organization of citizen science hubs or centers of scientific cooperation. The structural and functional model of formation of such competences in the framework of additional professional education is presented, taking into account the presence of the following factors: previous unsystematized knowledge, skills and abilities based on the librarian’s work experience; theoretical and practical training; application of the acquired knowledge, skills and abilities in practical activities immediately after successful completion of the advanced training course. Such realization is based both on the presence of external motivation of the librarian and on his/her knowledge of open science (most often related to the concept of open access) and principles of its functioning. Interactive forms and technologies are noted, including in the assessment phase, using remote working tools to keep the trainees motivated as well as integrating them into the open science environment. In addition, the specific working conditions of the librarian should be analyzed when selecting tasks — this can be a decisive factor in the personal interest of the learner. The basis for the implementation and testing of this approach is laid in three modules of the advanced training course “Library for Open Science” of the State Public Scientific and Technical Library of the Siberian Branch of the Russian Academy of Sciences. The results of the course show a high degree of development of skills linked to communication and project activities, but further adaptation of the material related to the legal framework is required.
