A method of processing lignocellulosic materials, comprising in combination the steps of - contacting the lignocellulosic material with an ionic liquid formed by a conjugate acid derived from an organic amidine or guanidine base and an acid, under conditions which are conducive to at least a partial dissolution of the cellulosic components of the lignocellulosic material, - recovering at least a part of the dissolved part of the lignocellulosic material by at least partial dissociation of the conjugate acid, - recovering at least a portion of the dissociated organic base and the acid, - forming a conjugate acid of the recovered base and acid, and - contacting the conjugate acid thus formed with lignocellulosic material in a method of processing lignocellulosic material, said ionic liquid being heated to a temperature in excess of boiling point at the prevailing pressure for recovering it by distillation, wherein the conjugate acid is an ionic liquid which contains anions and cations as solvent, the cation being derived from a substituted amidine base having Formula I or a guanidine base having Formula II wherein, in Formula I, R 1, R 2, R 3 and R 4 are the same or different and are selected from hydrogen, unsubstituted or substituted lower alkyl groups, aliphatic groups, heterocyclic groups and aromatic groups having 5 to 18 ring atoms, at least one of R 1, R 2, R 3 and R 4 representing an alkyl group having 1 to 6 carbon atoms, which is unsubstituted or optionally substituted; and wherein, in Formula II, R 5, R 6, R 7, R 8 and R 9 are the same or different and are selected from hydrogen, unsubstituted or substituted lower alkyl groups, aliphatic groups, heterocyclic groups and aromatic groups having 5 to 18 ring atoms, at least one of R 5, R 6, R 7, R 8 and R 9 representing an alkyl group having 1 to 6 carbon atoms, which is unsubstituted or optionally substituted; and wherein the unconjugated organic base has a ΔH PA value lesser than about -240 kcal/mol but greater than about -260 kcal/mol.; and the anion being derived from an acid having the general formula HX II wherein X stands for an anion selected from the group of halogen, sulphate, nitrate, nitrite, phosphate, phosphinate, carboxylate, sulphonate, organosulphates, organosulfonates, organophosphates, organophosphonates or combinations thereof, and wherein the anion of the unconjugated acid has a ΔH PA lesser than about -300 kcal/mol, preferably lesser that -320 kcal/mol and in particular lesser that -325 kcal/mol. - contacting the lignocellulosic material with an ionic liquid formed by a conjugate acid derived from an organic amidine or guanidine base and an acid, under conditions which are conducive to at least a partial dissolution of the cellulosic components of the lignocellulosic material, - recovering at least a part of the dissolved part of the lignocellulosic material by at least partial dissociation of the conjugate acid, - recovering at least a portion of the dissociated organic base and the acid, - forming a conjugate acid of the recovered base and acid, and - contacting the conjugate acid thus formed with lignocellulosic material in a method of processing lignocellulosic material, said ionic liquid being heated to a temperature in excess of boiling point at the prevailing pressure for recovering it by distillation,