[en] Hydroxyapatite (Hap) was synthetized with success by combustion reaction of aqueous system containing calcium nitrate, ammonium phosphate and urea. The effect of external heating temperature (muffle oven) on hydroxyapatite production was investigated. The material was characterized by X-ray diffraction, refinement by the Rietveld method, infrared spectroscopy and granulometric distribution. During the synthesis were measured the time, the reactional temperature and the color of the emitted flames were observed. The X-ray diffractograms presented tricalcium phosphate as the secondary phase. The different temperatures of synthesis resulted in samples with different amounts phases and modifications in crystallinity and crystallite size. The infrared spectra showed bands corresponding to the phosphate groups. Considering the results, the synthesis processed at 800 °C proved to be more viable for the hydroxyapatite production in higher percentage. (author)