We address the control problem of output tracking with disturbance rejection and preclusion of internal dynamics for multi-input multi-output nonlinear plants subjected to known disturbances. The closed-loop output error dynamics is required to be linear and noninteractive. Necessary and sufficient conditions for semiglobal solvability of the nonlinear control problem are given, yielding a construction of the related feedforward-feedback controller and identifying the basic information required on the measured and the assigned signals. The start-up of an open-loop unstable continuous free-radical homopolymerization reactor is considered as an application example. The solvability of the reactor control problem is characterized in terms of conditions that have direct physical meaning. Results are corroborated with numerical simulations.