Isothermal Fixed bed flow reactors are used as laboratory scale reactors for catalytic screening and kinetic studies of different solid catalysts for gas phase reactions. These are generally operated under dynamic conditions, whereby the reactants are continuously fed to the reactor and products are continuously collected for analysis. These are very important tools for developing new catalysts candidates for industrially important processes. All these reactors can be operated under a wide range of temperatures (from RT to 1000 °C) and pressures (up to 100 bar). All these reactors are equipped with Gas chromatographs for continuous on-line gas analysis.