Ferroelectric thin films of Sr0.8Ba0.2Bi2Ta2O9 were grown on Pt/TiO2/SiO2/Si substrates by using the pulsed laser deposition technique and the effect of annealing on structural and electrical properties of the films has been investigated. The films deposited at 500 degreesC substrate temperature and 200 mTorr oxygen pressure showed amorphous nature. Perfect crystalline films were obtained after annealing at 750 degreesC. Increase in grain size with increasing annealing temperature was observed by atomic force microscopy. Good hysteretic behavior with remanent polarization (2P(r)) of 11 and 25 muC/cm(2) and coercive field (E-c) of 32 and 34 kV/cm with fatigue endurance of up to 10(10) switching cycles were obtained with the films annealed at 750 and 800degreesC. Moreover, the films annealed at 800 degreesC had a maximum dielectric constant of similar to375. Increase in dielectric constant with increasing annealing temperature is attributed to the increased grain size, whereas the lower dielectric constant and higher dissipation factor of the 850degreesC annealed film is attributed to the presence of the secondary phase, which resulted from the loss of Bi due to evaporation and/or interdiffusion of metallic Bi into the platinum substrate at higher annealing temperature.