This work includes the study of the hydrolytic biodegradation of coatings based on polylactic acid, polyglycolic acid and hydroxyapatite. These coatings were obtained by cathodic electrodeposition over piezoelectric quartz crystals, using an electrolyte with different polymer/ceramic ratios but with a fixed time, voltage and volume of solvent. The films obtained were immersed into a simulated body fluid (SBF) during 1, 3, 5, 7 and 10 days at constant temperature and pH. The coatings were analyzed by EIS and QCM to find a correlation between frequency changes and the total transferred mass.