The main physico-chemical properties and the underlying influence of thermal treatment on the phase composition and structural characteristics of the natural phosphate Kef Esnoun region in Djebel Onk, Algeria, are discussed in this work. The primary goal is to increase the natural phosphate value as an alternative material in heterogeneous catalysis. The phase evolution during the heat treatment of the natural phosphate was carried out at different temperatures ranging from 600 to 1000 °C. Several complementary analytical methods were used for their characterization before and after thermal treatments. The obtained results by X-Ray Diffraction supplemented by the Rietveld method and confirmed by molecular spectroscopy have shown that the raw natural phosphate consists primarily of a fluorapatite-type structure (Ca 5 (PO 4 ) 3 F). Furthermore, hightemperature X-ray diffraction and thermal analyses have shown that dolomite which is one of the natural phosphate constituents is fully decomposed into CaO and MgO phases after heating at 700 °C. At 900 °C, the phase composition is (Ca 5 (PO 4 ) 3 F; 98.23 %), (MgO; 1.1 %) and (CaO; 0.67 %) with a crystallite size value of approximately 300 nm. Cell parameters increase with calcination temperatures due to the substitution of carbonate with PO 4 À 3 groups.