Increasingly frequent use of digital services of public institutions, digitalization of public administration results in exposure to cyber threats. At the same time, protection against cyber threats requires skills, knowledge and experience to enable defense and security against these threats. Although certain public institutions provide cybersecurity services to public, state and academic institutions, they are definitely not always sufficient and there is a need to cooperate with the private sector, which also offers certain cybersecurity services and products. The practice of cooperation between the public and private sectors in the cyber sphere should be well defined so that there are no gaps that will have implications for national security. This paper offers answers to three research questions. The first question is: What are the trends of cyber threats and what types of threats are represented at the EU and Croatian levels? The second question is: What are the strategic and normative acts that define the cyber security system of critical infrastructure in the Republic of Croatia? The third question is: What conditions are needed and how are they defined in the case of concluding public-private partnerships in the cyber sphere in the Republic of Croatia? In answering these three research questions, several research methods such as systems theory, inductive and deductive methods are used. When answering the third research question, the method of interviewing individual private companies that offer services or products in the field of protection of critical infrastructure from cyber threats is also used. Finally, we want to test the initial hypothesis that public-private partnerships in cyberspace contribute to the quality of cyber security in the Republic of Croatia.