Abstract. The influence of thermal annealing to TiO2 nanopowders doped with Fe atoms was investigated using coprecipitation method. Fe-doped TiO2 nanopowders were prepared using a cold titanium tetrachloride (TiCl4) and FeCl3. The samples were annealed at various temperatures from 200 o C to 500 o C during 60 minutes. Based on the X-Ray Diffraction results showed that the grain size of Fe:TiO2 nanopowders increased as annealing temperature was increased. This was due to the reducing of FWHM values in the X-RD spectra. FTIR results showed that the spectra were observed at 3417 cm -1 , 2358 cm -1 , 1645 cm -1 , and 518 cm -1 indicating the bond functional groups of O-H bond, C-O bond, O-H bond, and Fe-O bond, respectively. The agglomeration of Fe:TiO2 nanopowders into a large cluster were observed with scanning electron microscopy (SEM) when the samples were annealed at 500 o C.