This invention relates to the design of a process by intermittent dielectric heating combined with a recycling system.This process consists in subjecting reagents to electromagnetic waves selected in the frequencies ranging between 300 GHz and 3 MHz intermittently using a recycling system.This process enables the treatment of oils that are hardly absorbent as well as great investment savings.This process enables operation on different scales, whether in laboratories, on a semi-industrial or industrial scale, without forfeiting the advantages of continuous dielectric heating.