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TlBa2Ca2Cu3O9 superconducting films, 0.5 to 1 μm in thickness, have been prepared in a two step process. Using a nitrate solution, a precursor layer with composition Ba2Ca2Cu3Ox is first sprayed on a LaAlO3 heated substrate and then thallinated, following a procedure established for bulk samples. The critical temperature of the films ranges from 108 to 113 K, and the critical current density of the best samples reaches 0.7 MA/cm2. The reaction kinetics for the formation of the Tl-1223 phase between 880 °C and 910 °C has been studied for a better control of the grain growth and texture. The effect of fluorine addition on both the microstructure and superconducting properties have been also analyzed.