This book analyzes a variety of results related to the modeling, analysis, estimation, and control design and the applications of different configurations of tubular reactors of two classes of partial differential equations (hyperbolic and parabolic), both linear and nonlinear. The advantages of using the tubular reactor case to study distributed parameter systems (DPS) are that it covers: a large class of partial differential equations, the link between the PDEs of the tubular reactor models and the ODEs used for approximation for the practical application of state observation and control schemes, and a large spectrum of applications in biological, environmental and chemical systems.