Catalyst breakdown by physical attrition and chemical stresses is a problem of great and continuing concern in the slurry phase Fischer-Tropsch Synthesis. To reach a better understanding of the morphology and composition of a working catalyst, it requires first the removal of wax from the catalyst. In this work, Improved Soxhlet Extraction (ISE) in comparison of Standard Soxhlet Extraction was evaluated concerning their separation efficiency and relevancy for characterization of working catalysts. ISE extracted a greater amount of wax and recovered nearly all of the catalyst. In addition, ISE does not change the morphology and particle size distribution of working catalysts whereas Soxhlet extraction fails to reflect the actual information on the catalyst. The ISE is appropriate for the rapid and accurate analysis in plant operation.