As an environmentally benign, superparamagnetic material, magnetite (Fe3O4) has been a topic of interest for applications ranging from drug delivery to data storage. We report here investigation of magnetite as a lithium-battery material. While Fe3O4 synthesis has been widely studied, our approach afforded excellent crystallite size control without constraining media or elaborate equipment. Upon electrochemical testing, a strong correlation between performance and crystallite size was observed, resulting in a similar to 30% capacity increase. To the best of our knowledge, this is the first study of electrochemical effects of Fe3O4 crystallite size where all nanocrystalline samples were prepared using the same method.