Mosasaurus hoffmanni from Devrekani, Turkey is among the geologically youngest of the ancient aquatic predators. In addition, M. hoffmanni is the only Mesozoic vertebrate reported from Turkey, and has proven useful in the understanding of paleogeographic segregation within Mosasauridae. Here we provide an analysis of the histology and geochemistry of a functional maxillary tooth of this Turkish mosasaur. Dental histology included descriptions of lines of von Ebner and contour lines of Owen in dentine, as well as microstructural details pertaining to the enamel structure. Considering the spacing of the lines of von Ebner, the odontoblast deposition of the dentine (at the level of sectioning of the crown) was estimated to have taken approximately 511 days. A replacement tooth was fortuitously discovered upon sectioning the functional tooth, and given the thickness of the dentine visible, it is estimated that it took 233 days to deposit the centripetal layer of dentine. Energy dispersive spectroscopy, x-ray diffractometry, fusion disc x-ray fluorescence and Sr isotope measurements suggested that the tooth had undergone heterogeneous diagenetic alteration. Despite signs of alteration, the anatomy and chemistry of the M. hoffmanni teeth provided significant paleobiological and paleo-environmental insight.