This book lay emphasis on temperature control loop for designing of suitable controllers, using Internal Model Control. Temperature control loop can be modeled as Second Order process model with dead time (SOPDT), which is considered to be a complex industrial process. Importance of approximation techniques using various methods has been discussed in great detail. Various closed loop characteristics and modelling error, for step and impulse input, have been calculated for the selected and approximated process model. A comparative study has been performed to analyze the effect of dead time approximation and hence the overall performance of the system.