Calcium phosphates deposited by an electrochemical deposition process (ECD) have been prepared in the 0.04 M Ca(H2PO4)(2)center dot H2O (MCPM) solution at 10 V, 60 degrees C and 80 Torr for 1 h. Subsequently, the deposits have been treated in various concentrations of NaOH(aq) solutions at different temperatures for 1 h. When excess OH- is present in the ECD process, hydroxyapatite (HAP) referred to as pre-HAP is deposited oil the Ti-6Al-4 V substrate. After NaOH(aq) treatment, all deposits are converted to the HAP phase. The treatment in 1-2.5 M NaOH(aq) solution at over 60 degrees C offers a more proper environment for the HAP conversion, referred to as post-HAP, and has all average crystallite size of about 21 nm. For more than 5 M NaOH(aq) treatment, both pre- and post-HAP show a reduction of 5-20 nm in particle size. (c) 2005 Elsevier B.V. All rights reserved.