In this work we have studied weak processes such $\beta-$decay and neutrino capture that are very important for the r-process. This process takes place far from the $\beta-$stability line, that means in a region where data are very scarce experimentally. In order to study the nucleosynthesis of elements heavier than iron it is necessary to know the cross sections of neutrino-nucleus processes for these nuclei. We have fitted results obtained by Gross Theory of Beta Decay (GTBD) applied to neutrino-nucleus cross sections. We used a four degree polynomial dependence of the cross section with the incident neutrino energy in fitting Gross Theory theoretical results. This dependence allows us to systematically calculate the neutrino–nucleus cross sections for a large group of nuclei, such as those needed in the r-process (more than 4000 nuclei). Our fitting and interpolation procedures are shown to be in a good agreement and the GTBD cross sections are successfully reproduced.