An electric heating device based on a ribbon of crystalline metal foil with high specific resistance, which is additionally treated to increase its plasticity and/or additionally coated with a mold release agent to enhance compatibility of the ribbon and insulating envelope. The ribbon combines high electrical resistance, high stability, sufficient mechanical strength and relative cheapness with very important properties including significant plasticity and compatibility with insulating polymers, including rubber and silicone. The above compatibility provides high reliability and life span. Different structures for flexible and rigid heaters on the basis of this ribbon are described, as are different applications.