A new organosolv pulping method has been investigated. Delignification can be carried out by digesting the lignocellulosic material in an aqueous solution of ethylenediamine (EDA) and ethanol (EtOH) in combination with catalytic amounts of anthraquinone (AQ). This aqueous EDA-EtOH-AQ pulping is found to be highly selective in delignification and is flexible to softwoods. Bulk delignification was found to take place according to a pair of first-order mechanisms, like aqueous ethanol pulping. In the initial phase of delignification more than 50% lignin is removed, while the rest is extracted in the second slower step. The rate constants for each step are of the same order of magnitude and higher than those obtained in ethanol pulping. This indicated that overall delignification is faster when compared to aqueous ethanol pulping. The Arrhenius activation energy for the initial step was found to be 6.4 kcal/mole. The high selectivity in the detignification during the EDA-EtOH—AQ process is observed at all lev...