The present paper examines the problems of time critical systems. The core of the problem lies in dynamic resource allocation and time dependent functional changes of the systems. The extensive research is of crucial importance for system planning, performance evaluation, time synchronization, resource access control and system infrastructure. The formalism in a group of stochastic automata is also examined. The definitions of “time critical system” and “real time system” are given in a context of dynamic and stochastic systems. Such a system functioning is determined by a functional, logical and morphological description. The procedures of functioning can be specified in different ways: as macro models [2], and directed graph of procedures [4]. The mathematical approach to generalization of the above mentioned definitions has been proposed. This approach might be used for self organization of system infrastructure or making final decision. Finally, the paper presents the approach to optimization and design of critical time functioning systems.