This project proposes both theoretical and experimental approaches to improve the knowledge of beta spectra. On the theoretical side, we will use the existing knowledge of the calculation of nuclear wave functions to account for the nuclear structure effect on these spectra. On the experimental side, we propose the development of beta spectrometry with metallic magnetic calorimeters (MMCs), a class of cryogenic detectors operating at very low temperature, and solid scintillators containing the beta emitters in the structure of the scintillator crystal. These detectors have the potential to measure the shapes of beta spectra with unprecedented precision and, in particular in the case of metallic magnetic calorimeters, low systematic errors. Comparison of the newly calculated and measured spectra, as well as the application of several complementary detection techniques, will validate the quality of the spectra.