An interface including a substrate of biocompatible material such as titanium, tantalum or their alloys having, on the surface of the substrate, a first layer having a first concentration of oxide of the biocompatible material, enriched with a second concentration of phosphorus and with a third concentration of calcium, the ratio between the concentration of calcium and the concentration of phosphorus being greater than two. The interface also includes a second layer having a first surface in contact with the first layer and a second surface. The second layer has a fourth concentration of oxide enriched with a fifth concentration of calcium and a sixth concentration of phosphorus. The fourth concentration is less than the fifth and sixth concentrations and the ratio between the fifth concentration of calcium and the sixth concentration of phosphorus is no less than three.