A strain of At. ferrooxidans was isolated from Penjom Goldmine, Kuala Lipis, Pahang, Malaysia. The 16S rRNA partial gene sequence analysis revealed that this rod-shaped bacterium with size of 0.3 x 0.8 -m is a strain of At. ferrooxidans, and was designated as At. ferrooxidans KLipis-3-1. The whole-cell FAMEs profile analysis showed that At. ferrooxidans KLipis-3-1 possesses large amounts of C18:1, C16:0 and C16:1 fatty acids with C18:1 as the predominant fatty acid. The initial specific iron-oxidizing and molybdenum blue-oxidizing activities of this bacterium were 88.85 mMh-1mg-1 and 196.86 mMh-1mg-1, respectively, which were similar to the activities observed in the type strain At. ferrooxidans ATCC 23270. However, At. ferrooxidans KLipis-3-1 has a higher resistance towards Mo6+ at concentration above 1 mM. At. ferrooxidans KLipis-3-1 has the ability to reduce ferric ion with elemental sulfur as electron donor, with the initial specific SFORase activity of 0.47 mMh-1mg-1. The bioleaching capability of At. ferrooxidans KLipis-3-1 and At. ferrooxidans ATCC 23270 with pyrite as substrate at selected parameters operated in a batch bioprocess were studied.