Résumé : Pretreatments based on the oxidation of cellulose and ligno-cellulosic materials by sodium hypochlorite are compared with classical pretreatments ( Fe2+ H2O2, γ-rays, concentrated and dilute NaOH, Cadoxen, mechanical pulping). Substrates studied are paper pulp, wheat straw and spruce wood. The importance of oxidation and of transformation of cellulose I into cellulose II are discussed. Pretreatment of spruce wood by NaClO gives yields of glucose during enzymatic hydrolysis which compare very favourably with those obtained with the more expensive cadoxen and concentrated NaOH treatments. High yields of glucose are also obtained in the case of bagasse and barley straw. The work has been extended to other halogenated oxidizing agents. © 1986.