A method and an apparatus for increasing the temperature gradient of a magneto-calorific thermal generator comprising magneto-calorific elements subjected to a magnetic field variation. At least one of a pre-heating and pre-cooling of the magneto-calorific elements (60) is carried out to modify the initial temperature before and/or during the magnetic field variation before reaching the maximum and/or minimum field value. The method and apparatus may be employed in heating, tempering, air conditioning, refrigeration and other industrial or domestic applications.