The dynamics and control of two complex column configurations (sidestream column with stripper and prefractionater/sidestream column configuration) which are multivariable, interacting and nonlinear, have been studied, A new control scheme developed by Han and Park(4)) to deal with the nonlinear and multivariable nature of distillation processes has been applied to these complex distillation configurations. The control scheme incorporates a nonlinear wave model into a generic model control framework, An observer based on the nonlinear wave model is used to determine the profile positions of distillation column sections. The control scheme enables tight control of the profile position of each column section that leads to fast stabilization of product compositions.