This study aims to evaluate the effect of the time of maturation on the chemical and structural composition of the grains of phosphocalcicapatites doped out of oxygen. In the method of making the phosphocalcicapatites, a solution of calcium hydroxide Ca(OH)2 was neutralized with a solution of phosphoric acid H3PO4 in oxygenated-decarbonated medium at room temperature. The method could find future applications, for example, in the treatment of the infection of the bone. The apatitic fractions obtained present a well defined state of crystallinity and has an average specific surface (SS= 170 m2/g) relatively important compared with those of the phosphocalcic hydroxyapatite quoted in the literature. The adsorbed O2in the apatite structure influences considerably the specific surface of apatite. It reaches a maximum value of 183 m2/g after 6 hours of maturation and the content of O2 in the Oxygenated-Apatite (OA) reaches its maximum 1.7 % as in the first 10 minutes. The obtained results show the formation of an apatitic phase crystallized irregularly; once calcined with 900°C, the crystallinity of the phase becomes well organized. The thermal analyzes DTA and TGA show that the preparation phases undergo two losses of masses, a very weak one at 50°C, it corresponds to the water molecules adsorbed by apatite at the beginning and a second more important around 450°C and it corresponds to the loss of CO2. © 2017, University of Mohammed Premier Oujda Morocco.