The combined electrochemical and chemical methods with limited cost and green technology have been introduced for production of bone-like calcium deficient hydroxyapatite (HA) coatings on the Mg-alloy and glassy carbon surfaces. The potential assisted deposition allows the formation of films of controlled composition and morphology. At the same time cathodic polarization prevents the Mg-alloy decomposition. The mechanism and kinetics of the initial step of CaHPO4 electrocrystallization on the Mg alloy and glassy carbon (a model system for electrocrystallization processes) were studied in situ using chronoamperometry. The electrodeposited film was converted to Ca deficient HA via an acid-base reaction. The chemical composition and morphology of Ca deficient HA coatings were examined using XPS, SEM, and EDS. The barrier properties of HA coatings alone and those modified with monolayers of stearic acid were investigated by EIS in Hanks' solution. (C) 2013 The Electrochemical Society. All rights reserved.