The paper presents the results of the study of corrosion performance of HApcontaining coating obtained on the Mg-0.8Ca bioresorbable magnesium alloy using plasma electrolytic oxidation (PEO). Electrochemical measurements were carried out in minimal essential medium (MEM) using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) and monitoring of open circuit potential (OCP) techniques. It was established that the PEO treatment of Mg-0.8Ca leads to a significant increase in corrosion resistance of the material. Formation of heterooxide layer on magnesium alloy contributes to a decrease in corrosion current density (IC) more than three times. The impedance modulus measured at low frequency (|Z|f=0.1 Hz) for a coated material increased by two times compared to an uncoated one.