In order to use LOTOS to specify process control systems, first it is necessary to examine the differences between communication and process control systems, also going into some details specific to the latter . Seeing the difficulties first we have to discuss the possible advantageous use of LOTOS in that area, including the restrictions we have to face . Next, we will look at an example system, its modelling, and how it is possible avoid state space explosions in the specifications. After that , it is possible to set up a general model structure that is suitable for system analysis and formal specification. Finally, we will draw the conclusions and set some new targets to approach, which will make LOTOS a more powerful tool for the specification and design of process control systems.