Effects of post-deposition annealing was performed at different annealing temperatures (600, 800, and 1000°C) onto metal-organic decomposed lanthanum cerium oxide film spin-coated on Si substrate. X-ray diffraction analysis had detected four diffraction peaks of lanthanum cerium oxide in all of the investigated samples. Additional peak associated to lanthanum silicate (La2Si2O7) was detected in sample annealed at 1000°C. Electrical properties of the samples were investigated and it was found that sample annealed at 1000°C demonstrated the best metal-oxide-semiconductor characteristics in terms of giving the highest breakdown voltage and lowest leakage current density. Detailed explanation regarding this acquisition was discussed.