2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/8547Methanol lines observations of a sample of low mass Class 0 protostars are presented. Using a 1D radiative transfer model, I show that several protostars have large abundance jumps in the inner hot and dense region of envelopes, probably because of thermal grain mantle evaporation. These abundances are compared with a grain surface chemistry model.2 pages, 2 figures, Proceeding of the conference "The dusty and molecular universe", 27-29 October 2004, Paris, FranceAstrophysicstext