Problem setting. One of the cross-cutting lines of the current stage of public administration reform is the creation of a professional, efficient, effective, transparent and flexible system of executive authorities, which will be a prerequisite for the development of good governance in Ukraine. To do this, it is important to make the institutional capacity building (ICB) of such organizations. Institutional capacity is the ability of executive authorities to effectively achieve its goals, to maintain sustainable operation in the long run, to make high-quality public administration decisions with the broad involvement of beneficiaries and stakeholders.Recent research and publications analysis. Some aspects of the institutional capacity of public institutions have been the subject of domestic research by L. Kulish, O. Naumov, S. Brekhov, L. Naumova, O. Chemerys, M. Voinovskyi, N. Kolisnychenko, O. Ros, H. Shchedrova, K. Petrenko.Highlighting previously unsettled parts of the general problem. Despite a significant number of publications, the issue of the institutional capacity of the executive authorities still remains poorly explored in the science of public administration. Institutional capacity building instruments, one of which is an institutional audit, in particular, need to be further studied. The usage of institutional audit not only strengthens the institutional capacity of the executive authorities, but also forms the basis for the implementation of good governance approaches in the system of public administration. That is why the selected area of research is extremely important in modern conditions of public administration reform in Ukraine.Paper main body. The concept of audit at the present stage is no longer limited to financial control. The general audit methodology, which includes external assessment or self-assessment in accordance with established standards, establishing a certain current state of affairs, identifying opportunities for development and making recommendations, allows it to be adapted to all procedures, processes, operations and systems of any organization. But the purpose of the audit remains the same – to make sure that the functioning of the institution is carried out within a certain budget, goals, requirements or rules.The need to separate institutional audit from audit in public sector is due to current trends of the institutional capacity building of public institutions.To assist the executive authorities in the institutional capacity building, we use the institutional audit mechanism, by which we mean the instrument of public monitoring and control of institutional capacity of public institutions as the ability of these organizations to effectively achieve its mission and maintain long-term sustainability and quality of public services as a result of public administration functions performed by public institutions. And although the institutional audit is essentially part of the public administration function of monitoring and control, it is focused not on identifying violations and further application of sanctions to responsible persons, but on finding potential for institutional development of executive authorities, effective and efficient performance of its functions.The institutional capacity building of executive authorities involves increasing its capacity for sustainable, consistent and reliable implementation of goals and objectives. In practice, it means improving the organization’s management system, including decision-making, financial management, human resource management processes, establishing effective internal and external communication, and so on.An important component of institutional audit is the actual assessment of institutional capacity, which aims to outline the organizational and behavioral aspects of the system that contribute to its efficiency. Through evaluation, the executive authorities receive a diagnosis of the internal environment, processes and goals, as well as a better understanding of the role of all stakeholders. The results of the assessment are the answer to the question “What are the shortcomings in the planning, implementation and effectiveness of a particular executive authorities?”. And every shortcoming identified today is a potential opportunity for development tomorrow.The efficiency of the institutional capacity assessment process and institutional audit in general depends on many factors, which can be divided into internal and external. Internal factors, as a rule, relate to the transparency of the executive authority, in particular the interest and willingness of its management to communicate with auditors, the presence of the request of the institution itself to undergo an institutional audit. Instead, external factors in the efficiency of institutional audit are more concerned with involving stakeholders in this process. Moreover, researchers and experts consider the involvement of stakeholders not only as subjects of the audit process, but also as drivers for the implementation of measures to increase the institutional capacity of the executive authority.In this context, we consider it appropriate to involve the public in the face of non-government organizations (NGOs) as independent institutional auditors. In particular, these may be organizations or coalitions of organizations operating in a field similar to a public institution. For example, NGOs working with people with disabilities could conduct institutional audits for social policy departments of local government administrations.The process of the institutional capacity building of executive authorities doesn’t give immediate results, because it is accompanied by changes within the organization, which always, despite the positive or negative, cause resistance from personnel. Add to this the over-bureaucratized structures and processes of public administration decision-making, the prevalence of political expediency over economy, efficiency and effectiveness, and the lack of a strategy, but also a clearly defined mission, in most executive authorities, we will be given an incredibly difficult task for an institutional audit. However, without overcoming these obstacles and ensuring sustainable institutional development of public institutions, it is impossible to form an effective system of public administration or build a democratic, social and legal state.Conclusions of the research and prospects for further studies. The institutional capacity building of the executive authorities is an important step towards implementing the concept of good governance in Ukraine and bringing public institutions to a qualitatively new level of functioning. Harmonization of such key components of a public institution as mission and vision, management system, corporate culture, organizational structure, communication within the organization and with the external environment, staff training and motivation system, work practices and procedures, will allow executive authorities to implement its tasks and achieve the objectives. And the continuous connection with the beneficiaries and stakeholders present in the institutional audit will increase the transparency and parity of the government’s interaction with the public, which is the key to the democratization of public relations in the state.However, in the domestic realities, institutional audit does not have sufficient methodological and regulatory support, and what is available is scattered between different laws, regulations and even types of audit. Systematization of legal bases of institutional audit and strengthening of methodological basis of its carrying out is a key direction of further scientific studies.