A bioactive hydroxyapatite layer deposited on the CoCrMo bio-metallic alloys by electrodeposition under different concentrations of calcium, phosphate and H2O2. Response Surface Methodology (RSM) and Central Composite Design (CCD) were used to optimize electrolyte concentrations. RSM and CCD were used to understand the concentration effects on the in vitro corrosion performance of biomaterials. 5-level-3-factor CCD was employed to evaluate effects of deposition parameters such as calcium concentration (0.016-0.184 M), phosphate concentration (0.005-0.055 M) and H2O2 concentration (2.4-27.6 ml/L) on the hydroxyapatite coatings and their corrosion resistance. Data obtained from RSM were subjected to analysis of variance (ANOVA) and analysed using a second order polynomial equation. Optimum conditions for the deposition parameters of the hydroxyapatite layer coating were found to be a calcium concentration of 0.05 M, phosphate concentration of 0.04 M and H2O2 concentration of 22.11 ml/L. Maximum phase angle under the optimum conditions was determined to be 85.4 degrees. Ringer's simulated body fluid was used for in vivo electrochemical impedance spectroscopy analyses of biomaterials. (C) 2014 Elsevier Ltd. All rights reserved.