Softwood lignocellulose is a potential feedstock for the production of biofuels and bioproducts. However, the highly cross-linked nature of softwood lignocellulose restricts enzyme access to its sugars. Thus, harsh pretreatment conditions (180?280 �C) and/or high enzyme loading are required to unlock sugars. These requirements negatively affect the economic viability of softwoods in biorefineries. Here we show that H<
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3<
/sub>
PO<
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4<
/sub>
pretreatment of pine and Douglas fir under a mild reaction temperature (50 �C) and atmospheric pressure enabled a high (~80%) glucan digestibility with low enzyme loading (5 filter paper units (FPU)/g glucan). The dissolution and regeneration of softwoods disrupted the hydrogen bonding between cellulose chains, thereby increasing the cellulose accessibility to cellulase (CAC) values by ~38-fold (from ~0.4 to 15 m<
sup>
2<
/sup>
/g biomass). Examination of H<
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3<
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PO<
sub>
4<
/sub>
-pretreated softwoods by cross-polarization/magic angle spin (CP/MAS), <
sup>
13<
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C- nuclear magnetic resonance (NMR), and Fourier-transform infrared spectroscopy (FTIR) revealed that breaking of the orderly hydrogen bonding of crystalline cellulose caused the increase in CAC (higher than 11 m<
sup>
2<
/sup>
/g biomass), which, in turn, was responsible for the high glucan digestibility of pretreated softwoods. The H<
sub>
3<
/sub>
PO<
sub>
4<
/sub>
pretreatment process was feedstock independent. Finally, 2D <
sup>
13<
/sup>
C?<
sup>
1<
/sup>
H heteronuclear single quantum coherence (HSQC) NMR showed that the lignin was depolymerized but not condensed
thus, the lignin can be available for producing high-value products.