Cadmium hydroxyapatite (Cd-Hap, Cd-10(PO4)(6)(OH)(2)) and cadmium hydrogen phosphate hydrate (Cd5H2(PO4)(4)center dot 4H(2)O) nanostructures with average crystallite sizes of about 38 and 44 nm, respectively, were prepared through a simple chemical process. The formation mechanism and characteristics of the Cd5H2(PO4)(4)center dot 4H(2)O precipitates prior to the hydrothermal process and Cd-Hap during the hydrothermal treatment were investigated with XRD, SEM, TEM and BET analyses. It was found that self-assembled dahlia-like Cd5H2(PO4)(4)center dot 4H(2)O nanostructure precipitates were formed due to interlace of preliminary nanosheets prior to the hydrothermal process, while nanostructure Cd-Hap hexagonal prisms were prepared after 15 h of hydrothermal treatment. (C) 2007 Elsevier B.V. All rights reserved.