<b>Conceptual Design for Real time Monitoring and Control System for critical assets using JAVA Classes Case Study of Public Building and Oil and Gas Pipeline security</b> Critical public assets such as oil and gas pipelines, public buildings, power plants, nuclear plants, public water utility etc needs to be monitored in real time so as to ensure their availability, dependability, safety and security. In this paper, we examined the basic components and architecture of real time system, which includes real time control, data acquisition system DAS , critical systems, sensors and actuators, stimulus and response, Multi Agent System MAS design procedures and implementation of real time systems using JAVA Standard Edition SE programming paradigm known as Java classes. We also examined the pros and cons of JAVA as a programming language compared to other languages such as Assembly Language and Ada. The paper went further to present the design and process architectures and timing requirements for two critical public assets the oil and gas pipeline and public building involving different types of sensors and actuator interfaces. The paper concluded by implementing JAVA classes for the burglary alarm intruder detection system capable of detecting and reporting any intrusion targeted at critical public buildings. real time, response, stimulus, JAVA classes, actuator, sensor, critical systems, Multi Agent System, data acquisition system, pipeline, public utility, building, alarm, alert, vandalism 1675-1684 Issue-3 Volume-2 Engr. Fidelis C. Obodoeze | Dr. Ndidi Fidelia Ugwoke | Edith Angela Ugwu