A gas-agitated multiphase reactor system with multiple reaction zones comprising gas-liquid or gas-liquid-solid mixtures that can maximize the production rate while allowing better control of the temperature distribution and better control of the liquid and solid phases in the reactors. Still more particularly, this invention relates to a method for operating a pair of linked gas-agitated slurry reaction zones such that the hydrodynamic behavior and reactor performance of such reactor system are improved compared to that of a conventional slurry bed reactor