Abstract: A method for pulping a fibrous lignocellulosic material includes a pretreatment step wherein the lignocellulosic material is reacted with a chelating agent selected from the group consisting of amino acids, monocarboxylic acids and polycarboxylic acids preferably having from two to six carbon atoms. The chelating agent reacts with calcium ions in the material to form stable, water-soluble calcium complexes so as to avoid scaling, and the treated material requires a significantly lower energy input to undergo refining using either a mechanical or thermomechanical pulping method.