The chemistry of the reaction of coal with methanol and sodium hydroxide involves not only hydrogenation, mainly through the mechanism of hydride transfer from alcohol anion, and alkylation of aromatic systems but also several other types of coal structure transformations : hydrolytic cleavage of bonds, mainly ether bridges, and elimination and chemical blocking (O-alkylation) of oxygen functional groups. Coal solubilization by reaction with methanol and sodium hydroxide is a result of combined effects of the above transformations. In this study, the effects of a preliminary reduction of carbonyl groups with lithium aluminium hydride and/or of a preliminary O-methylation with dimethyl sulfate on the conversion of the Kansk-Achinsk lignite under methanol-sodium hydroxide solubilization were investigated by means of structural characterization, sequential solvent extraction, and programmed pyrolysis of the lignite and of its solubilization byproducts. In spite of a decrease in susceptibility to hydrogenation and alkylation reactions, which otherwise play a critical role during the CH3OH-NaOH treatment of bituminous coal, blocking of the numerous free carboxyl and hydroxyl groups of the lignite increases the conversion yields, as a result of a prevention of repolymerization reactions. O-Methylation of the hydroxyl groups released by hydrolytic cleavage would also stabilize the reactive oxygen groups of the lignite.