Flat non-linear systems are linearizable by quasi-static feedback of generalized states. As a consequence, stable tracking of reference trajectories can be achieved with controllers which do not introduce extra dynamics into the loop. If, moreover, the system has a series structure, this may be exploited for simplifying the flatness-based analysis and design. The resulting method is illustrated on a series connection of two chemical reactors. Flatness-based analysis of the stationary solution and-using these results-the design of reference trajectories which account for constraints are discussed in detail. Quasi-static feedback controllers are designed and some simulations are reported.