The design and operation of a graphite element drop‐tube reactor system for a study of the fundamental mechanisms and reaction rates of sulfur dioxide (SO2) removal by high‐temperature injection of limestone‐based sorbents is described. The reactor system is designed for laminar flow in an environment that allows for control of reaction temperature, sorbent particle residence time, and atmosphere composition. The sorbent injection system allows variable feed rates to as low as 1 mg/min for particles as small as 1 &mgr;m in diameter. The water‐cooled sorbent collection system arrests the high‐temperature reaction upon capture and allows analysis of the sorbent’s efficiency of SO2capture andinsituparticle‐size distribution. The results presented show the reactivity of different types of sorbents at varying conditions of system operation.