Abstract
The paper shows a series of data concerning the formation and lignin nature of polymeric deposits built up at the beechwood pre-hydrolysis. By means of elemental compostion, data limit formulas (empiric) of deposits have been calculated also emphasizing the special influence of hidromodule over the structure of deposits. The second part of the paper shows aspects related to the recovery of lignin polymeric deposits in order to synthetize a lignin-phenol-formladehyde resin, useful to the wood processing sector as well as the energy sector. Keywords: pre-hydrolysis, beech, limit formulas (empiric), lignin-phenol-formaldehyde resins