A theoretical and experimental investigation on the electron impact ionization in silicon has been carried out in the temperature range between 300 and 773 K. The impact-ionization model proposed here is based on the solution of the Boltzmann transport equation. The results show that the ionization coefficient is strongly dependent on the temperature and the electric field. The experimental results are in good agreement with the theoretical predictions, confirming the validity of the proposed model. The study provides valuable insights into the mechanisms of electron impact ionization in silicon, which is crucial for the development of advanced semiconductor devices.