This article present the implementation of RGA and RNGA algorithm for a approximated model of interacting thermal process. Also decentralized controller has been implemented. Both the steady state and transient information of the process transfer function are investigated. These algorithms make the closed loop system linear in an input output sense. MATLAB simulation results for the multivariable process show that the RNGA based control technique gives less Settling Time (Ts) and Integral Square Error (ISE) when compared with the conventional RGA based control technique. Simulation results validate the algorithms used. © Research India Publications.