Microcapsules containing tri-n-octylamine (hereafter TOA) as an extractant were prepared by using SPG membrane emulsification and in-situ polymerization. The morphology of microcapsules, the encapsulation efficiency of TOA, the extraction of palladium from hydrochloric acid solution and the back-extraction of palladium from microcapsules were investigated. The average diameter of the microcapsules was half of the pore diameter of the SPG membrane. The encapsulation efficiency of tri-n-octylamine was nearly 100%, and thus there was practically no loss of TOA during the preparation of microcapsules. Microcapsules pretreated with hydrochloric acid were equilibrated with palladium chloride hydrochloric acid solution, and the extraction properties were determined by measuring the concentration of residual palladium. The extraction of palladium occurred promptly, and all microcapsules prepared in this study reached equilibrium within 10 minutes. To examine the back-extraction of palladium from microcapsules, microcapsules were shaken in thiourea solution or hydrochloric acid until back-extraction equilibrium was reached. The results of extraction and back-extraction experiments indicated that TOA was completely encapsulated and there was no leakage of TOA, thus the microcapsules could be used repeatedly for extraction.