Hydroxyapatite was formed on zirconium at different current densities by single-step plasma electrolytic oxidation. The amount of hydroxyapatite and calcium-based phases increased with increasing current density. The bioactivity of hydroxyapatite based coatings was significantly improved compared to zirconium and zirconium oxide. The microbial adhesion of the coatings decreased with increasing current density was greater than one of zirconium. Cell attachment and cell viability were significantly improved compared to uncoated zirconium.