The applicability of static decoupler followed by tuning of diagonal proportional integral controllers for unstable multivariable process is studied. The need of static decouplers for an unstable multivariable system where the conventional decouplers becomes unstable is brought about by using three examples of a two-input two-output processes. Further, dual loop controllers are tuned for the approximated decoupled system. Use of P-PI (Proportional – Proportional and Integral) dual loop control system reduces the overshoot significantly. © 2015 Indian Institute of Chemical Engineers.