Object of research: public administration in the field of state security. Objective: substantiation of the development of the institute of lobbying as a basis for ensuring the state security of Ukraine and development of a theoretical model of the mechanism of the institute of lobbying implementation in the system of state security of Ukraine. Methods: logical-dialectical, system analysis and synthesis, comparison, abstraction, systematization, system approach, comparative law, modelling. Results: the topical problem of the theoretical foundations of the institution of lobbying as a basis for state security of Ukraine and the development of practical recommendations for improving the mechanism of the institution of lobbying implementation has been solved. Novelty: a theoretical model of the mechanism of the institute of lobbying implementation as a basis for ensuring the state security of Ukraine has been developed, its main components include: firstly, introduction into operation the National Council of Ukraine on lobbying regulation; secondly, the introduction of an electronic register of lobbyists of Ukraine; thirdly, the introduction of the lobbyists’ reporting forms, forms of control over their activities; fourth, the definition of requirements for persons who may belong to lobbyists; fifth, the adoption of codes of ethics, taking into account cooperation with lobbyists, determining the terms of cooperation, reporting on the activities carried out; sixth, the definition of lobbying methods; seventh, the definition and establishment of a system of public authorities involved in cooperation with lobbyists; improved: the main functions of lobbying in the state security system which differ from the existing ones by substantiation of four main clusters of functions: economic, organizational, communicative and protective; systematization of problems of the institute of lobbying development in Ukraine characterized by separation of six clusters of problems of the institute of lobbying development in Ukraine, systematization of regularities of the institute of lobbying development abroad; further developed: conceptual and categorical apparatus of the research; it has been found out that lobbying in the state security system is a form of representation of group interests which are aimed at ensuring state security of Ukraine, minimizing threats to national security, influencing public administration decisions aimed at ensuring nationally important interests of the state; systematic analysis of the mechanism of formation and development of the institution of lobbying in Ukraine. Implemented in the activities of: Verkhovna Rada of Ukraine, the First International Development Fund of Ukraine, NGO “All-Ukrainian Assembly of Doctors of Science in Public Administration. Application field: public administration, local and self-government, NGOs
