A dielectric heating system with which the power density applied to the product being treated can be at least doubled without risk of electric arcs. This invention is particularly suitable for treatment of compounds that absorb electromagnetic waves weakly (low dielectric constants). In particular, fatty substances such as oils, butters, waxes and fats can be treated (refining, hydrolysis, transesterification, interesterification, etc.), derivatives thereof (esterification, polymerization, alcoholysis, ethoxylation, hydrogenation, etc.) under static or dynamic conditions, as can hydrocarbons and aromatic compounds. This system can also be used advantageously for polar or polarized compounds, because the power absorbed is increased very significantly, with large production gains. In particular, fatty or non-fatty alcohols (oleic alcohol, glycol, glycerol, mannitol, sorbitol, polyglycerols, vitamins, etc.), carboxylic acids, amines and similar compounds can be treated under static or dynamic conditions.