The design of chemical reactors, especially the safety design process, requires basic knowledge of all particular processes proceeding in the reactor, and their influence on the reactor behaviour. A useful tool for safety analysis is a mathematical model of the reactor. By simulation of its performance one can reveal the real reactor behaviour. In the present paper, we tried to formulate and discuss the guidelines for safety analysis of a chemical reactor. In this article, a homogeneous CSTR was assumed, but some considerations could be extended for other types of homogeneous reactors. A program tool using nonlinear analysis of the studied system is presented.