A combined apparatus for heating, cooking, grilling and defrosting of foods of various kinds, depending on the type of foods to be treated from time to time and the duration of the foods treatment foreseen by each user of the same apparatus, where each hot treatment of foods may be effected either by heating or by microwaves only, or by heating and microwaves combined to each other. There are described in detail all the technical characteristics of the apparatus and the relative control circuits either for heating or for generating the microwaves. Advantages include use of a sole and single apparatus for hot treating the foods for providing for the heating, the cooking, the grilling and the defrosting of the same foods, instead of employing as it happens hitherto of single separated apparatuses for performing the same functions.