Wood chips of Ailanthus altissima and Spruce orientalis were delignified in either glycerol or alkaline glycerol process, at atmospheric pressure, for the production of pulps. For a typical run, increasing the reaction time and the reaction temperature from 438 to 498 K raises the yield of the removed lignin from 56.2 to 87.9% but decreases the yield of the recovered cellulose from 91.0 82.7% by using 10% sodium hydroxide catalyst, for a 9 hours reaction time (for Ailanthus altissima). Without using any catalyst, the same yields were found as 48.7 - 77.4% for lignin, 96.0 - 92.6 % for cellulose, in the same range of temperature and reaction time. Within the range of reaction parameters studied: temperature (438 - 498 K), catalyst (sodium hydroxide or sodium carbonate), amount of catalyst (5.0 - 10.0 wt % of used sample), chip size (0.3 mm x 15 mm x 15 mm or 2 mm x 15 m x 15 mm) and role of the glycerol, temperature and chip size were the most important variables. The pulp yield obtained by this method was 52 % and kappa number was 15.7 (for Ailanthus altissima).