The olivine structured LiMnPO4/C composites were prepared by a combination of spray pyrolysis and wet ballmilling using different conductive carbons: acetylene black and two types of ketjen black. The ketjen black with a larger specific surface area and dibutyl phthalate absorption number was found to be more preferable compared with other conductive carbons studied in this work. The LiMnPO4/C composite cathode with ketjen black, which has the largest specific surface area, exhibited the largest discharge capacity compared with other LiMnPO4/C composites. The largest discharge capacity delivered by this composite cathode was 166mAhg−1 at 0.05C, which is about 97% of the theoretical value for LiMnPO4. The performance improvement by using this conductive carbon was attributed to its extremely large specific surface area and high ability to absorb the electrolyte, which provide enhanced charge transfer and lithium ion transport in the composite cathode structure.