Laboratory studies for direct causticizing process by ferric oxide in soda quinone pulping of softwoods (Douglas fir and pine (Akamatsu)) were carried out in comparison with kraft and borate kraft pulping. DDA (1, 4-dihydro-9, 10-dihydroxyanthracene sodium salt) was used as quinone with addition of 0.05-0.15% as AQ by weight on o.d. wood. Pulp yield and Kappa number were determined, and the quinone addition of 0.1% in soda quinone pulping increased the delignification rate to equal that of kraft and borate pulping at the sulfidity of 25% without reducing pulp yield. Bleachability of soda quinone pulp was slightly lower than that of kraft and borate kraft pulp, and the viscosity of bleached soda quinone pulp was 7-9 cp lower than that of kraft pulp. The pulp properties of soda quinone pulp were nearly equal to that of kraft and borate kraft pulp except tear strength of low Kappa number Douglas fir pulp and burst and tensile strength of pine pulp.