The article is dedicated to solving a topical issue concerning the provision of information security at objects of critical infrastructure. Information security providing is a priority task and a basic precondition for the effective functioning of the objects of critical infrastructure in the current conditions. The purpose of this article is the development of research methods, analytical procedures and mathematical models for the forming of the complex system for information security providing to the critical infrastructure object. The article presents theoretical and methodological foundations of the strategic management of information security of the objects of the critical infrastructure. Assessment of conditions for the implementation of the information security system is one of the most important principles of the critical infrastructure activity, which provides the complex information about material, economic and financial capabilities of the object of the critical infrastructure. System analysis, mathematical modelling, analysis and synthesis methods have been used. The main results of the research are following: the model and method for research conducting of the conditions for the implementation of the information security system to the object of the critical infrastructure have been formed; the complex index for the assessment of conditions for the implementation of the information security system has been determined; the multivariable regression model which determines the relationships at the potential estimation level of the production component has been calculated and the complex system for providing of information security to the object of the critical infrastructure has been proposed