In the earlier report13, 6) of this series, it was shown that pulp yield by alkali-methanol cooking is 25% higher than that by kraft cooking and both pulps are similar in sheet strength. It was also elucidated that the rapid delignification during alkali-methanol cooking is due to the prevention of condensation through methylation of active benzylalcohol groups in lignin molecule. Recovery of methanol in spent liquor was also discussed2) .The present paper is concerned with the behaviors of lignin and carbohydrate during alkalimethanol cooking. Model experiments were carried out by the use of guaiacylglycerol-β-guaiacyl ether as a lignin model substance, and by the use of hydrocellulose and cellobiose as carbohydrate model substances. Each model substance was cooked in alkali-methanol [(40 g NaOH+400 g MeOH) /l ] and soda [40 g NaOH/l] cooking liquors under various cooking conditions. Results obtained are as follows : a) The yield of guaiacyl produced by the clavage of β-ether linkage of guaiacylglycerol β-guaiacyl ether was lower in alkali-methanol cooking than in soda cooking (Table 1). It is noteworthy that the kraft-like rapid delignification can be attained in alkali methanol cooking, although the rate of, β-ether cleavage is slower than soda cooking.b) Guaiacylglycerol-β-guaiacyl ether was methylated at the α-position of side chain. A methylated compound was isolated and identified by mass spectrum and 13C-NMR of it (Fig. 13). The mechanism of methylation was discussed by the analysis of 13C-NMR and assumed to follow the SN 2 (Fig. 4).c) Residual hydrocellulose after alkali-methanol cooking was 12% higher than soda cooking (Table 2). Corresponding to this result, the yield of gluco-isosaccharinic acid produced by peeling-off reaction was lower in alkali-methanol cooking than in soda cooking.d) Residual cellobiose depends on the concentration of methanol in alkali-methanol cooking liquor (Fig. 5). It was shown that the higher the concentration of methanol, the more the residual cellobiose.e) It can be concluded from the above-mentioned results that the peeling-off reaction was suppressed in alkali-methanol cooking. This may suggest that the isomerization rate of a glucose end group to a fructose end group is slower in alkali-methanol cooking liquor than in soda cooking liquor.