. The aim of the study is to develop a methodology for determining critical processes in order to simplify the activities of critical information infrastructure (CII) entities for categorizing information infrastructure objects the example of the chemical industry. The actuality of the problems under consideration is based the fact that the number of cyber attacks in various areas of state activity, including significant objects (ZO) of CII, is not decreasing. To protect the national information resources of the Russian Federation in 2017, the actions have been chosen in the direction of protecting CII objects with the adoption of the Federal law on the security of critical information infrastructure of the Russian Federation, which defined important directions of the Russian state policy in the information sphere for the next decade. Thus during its implementation, many subjects of critical information infrastructure have already had to face difficulties of various levels. The paper analyzes some fragments of solving the tasks set in the development of methods for determining critical processes at information infrastructure facilities, the sustainable functioning of which is regulated by a number of fundamental regulatory legal documents of the Russian Federation. In the course of the study, some features of determining critical processes at CII facilities, for example, in the chemical industry, were established. These features were later used in the development of a unique methodology for determining critical processes in the information infrastructure.