In this study, in order to increase the adhesive strength of a Hydroxyapatite (HA) coating, deposited on the surface of commercially pure titanium, acid passivation and hydrogen sputtering pretreatments were used. The pure titanium surfaces were passivized by acid solution and treated by hydrogen sputtering, at a temperature of 300 degrees C for 1 h. Ca(NO3)(2)center dot 4H(2)0 and NH4H2PO4 were chosen as starting precursors for Ca and P sources. HA coatings on the titanium surface were deposited using the sol gel method and sintered in air at the temperatures of 750 degrees C-900 degrees C for 1 h. XRD, SEM, EDS and AFM analysis techniques were used for structural and morphological characterization. Scratch test was performed for determining the adhesion of HA coatings. The experimental results indicated that compact and crack free HA coating, which has a Ca/P ratio of 1:6, was formed on pure Titanium (Ti) surface. The adhesive strength values of the HA coating, pretreated with H-2 sputtering and acid passivation were found to be 72.84 MPa and 55.83 MPa at temperature of 900 degrees C, respectively. It was observed that H-2 plasma sputtering pretreatment, improved the adhesive strength of the HA coatings compared to pretreatment with acid passivation. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.