Neutrino is the most mysterious particle among those already met by physicists. The definition of its nature is still open: Dirac or Majorana ? The only approach with reasonable chances to learn about is the observation of the double beta-decay not accompanied by neutrino emission. An experiment aiming to solve the dilemma has to reach extreme figures both in energy resolution and in background rejection rate. The bolometric technique is the most promising one. In this seminar perspectives for experiments of a generation next to that of those presently under construction will be discussed.