A two-step synthesis process was performed to obtain TlBa2Ca2Cu3Ox (Tl-1223) superconductor films. The synthesized films were obtained under different thallium diffusion conditions in a two-zone furnace precursor films were deposited at 550◦C on silver substrates using the spray pyrolysis technique from acetylacetonates (2, 4-pentanedionates) as reagents. Second, a thallium diffusion process is carried out to incorporate Tl in the films. For this task Tl2O3 pellets, as a Tl source, were used at 750◦C. Different oxygen flow rates at atmospheric pressure were used in order to get the thallous oxide p(Tl2O) partial pressure in the range of 6.9×10−4 to 6.1×10−2 atm. The Tl-1223 phase was obtained in all cases, though for a low p(Tl2O), the films presented the BaCuO2 phase mixed with the Tl-1223 one. Critical temperature (TC ) values for these films were in the range of 90 to 102 K.