The composition, structure, and thickness of the oleate self-assembled layers on apatite have been determined by a method based on experimental infrared reflection data. This work demonstrates the versatility of the proposed method. The advantages and limitations of this method are examined and explored in detail. From the analysis of the reflection spectra of the same sample recorded at specific angles of incidence and different polarizations, the orientations of the carboxylate group and hydrocarbon chain with respect to the surface normal were calculated. The use of the absorbance components instead of the electric field components is proposed in this evaluation. The studies were performed on three samples characteristic for different stages of adsorption layer formation. At close to monolayer coverage, the major part of the adsorbed molecules is well-organized, and two different structural domains are observed. The average orientation angles between the transition moment of the asymmetric stretching vibration of the two types of carboxylate groups and the surface normal are 83 degrees and 62 degrees. These two well-distinguish orientations of the carboxylate group are proposed to be associated with two different types of calcium sites present at the (100) plane of apatite. At a coverage close to two statistical monolayers, the molecules adsorbed on the top of the first well-ordered layer are randomly spread and oriented almost parallel to the interface. There is a very low intermolecular interaction between them, which is contrary to a strong lateral interaction in the first close-packed layer. Apatite with multilayer coverage (about 10 statistical monolayers), produced by the surface precipitation mechanism, shows a well-organized structure, with two different orientations of the carboxylate groups, which are very similar to those observed at close to monolayer coverage. The observed water molecules in the adsorption layers play an important role in the formation of organized surface structures.