Supernovae have a deep impact in many fields of modern astrophysics and cosmology, from stellar evolution theory to the model of galaxies chemical evolution to the measurement of cosmological parameters. We are expecially interested in their role as tracer of stellar population and distance indicator at high redshift. In this thesis we will analize the observations of a sample of SNe (not only type Ia) at redshift z>0.2, which have been discovered during a SN search at ESO+WFI and for which spectra have been obtained with VLT+FORS. The high-z SNe will be compared with local object to search for possible evolution.