Polycrystalline SrFe12O19 thin films were deposited on Si (100) substrates by PLD using a Nd-YAG laser ((lambda) equals 1064 nm). During the deposition process substrates were kept at room temperature. As-deposited films were annealed in air at temperatures between 600 degree(s)C and 840 degree(s)C. Samples were characterized by AES, ESCA, SEM, AFM, x-ray diffraction and VSM. It is presented the relevance of the preparation of the target surface on the film quality. Some differences in the chemical composition of as-deposited films, compared with the target and the annealed films, were observed. The x-ray diffraction spectra show a textured as- deposited films. Samples annealed at 600 degree(s)C, and below, showed a very weak magnetic response. In contrast annealing in the temperature range 700 degree(s)C - 840 degree(s)C led to the formation of a nanocrystalline particle system (average particle size 150 - 350 nm) which behave as a single domain in the thermally demagnetized state. The obtained coercivities (5750 - 6850 Oe) are among the highest values reported for films, powders and sintered samples.