Since Sasol introduced the Kellogg designed circulating fluidized bed (CFB) reactors at Sasol 1 in the 1950s, the commercial high-temperature Fischer-Tropsch (HTFT) process has had a dynamic ongoing development resulting, recently, in the introduction of Sasol advanced synthol (SAS) reactor operation only at Secunda, 1999. It has reached a stage now where the emphasis has shifted for developing a catalyst tailored to these reactors and current market requirements. This paper follows the development of the reactor technology since the early 1940s, highlighting the major developments and giving indications of the effect thereof on gas throughput and bulk product yields. The paper traces Sasol's journey utilizing the sound, but unproven pilot plant scale-up of Kellogg, to a routine day to day operation and profitable commercial process by means of innovative design changes, general state-of-the-art advances and, importantly, experience!