Low cost processing of lignocellulosic biomass is of great importance for sustainable chemistry and engineering. Herein

a low cost system composed of 1-butyl-3-methylimidazolium chloride ([C

4

C

1

im

]

Cl)

HCl and formaldehyde (FA) was developed for the pretreatment of corn stalk at 80℃. The efficiency of this technology was compared with that in dioxane system or without FA addition. Due to FA stabilization

the extent of acid-hydrolysis of carbohydrate fraction can be significantly decreased while 70% above of lignin was removed with the pretreatment of[C

4

C

1

im

]

Cl/HCl/FA system at 80℃ for 2 h. A maximum reducing sugar yield of 93.7% and glucose concentration of 7.0 mg·ml

-1

were subsequently obtained from enzymatic hydrolysis of the slurry. There were great differences in compositions of small molecule degraded products obtained with FA addition or not. The present[C

4

C

1

im

]

Cl based system exhibits great potential of substituting volatile organic solvents (

i

.

e

. dioxane) in developing low cost lignocellulosic biomass pretreatment at low temperature. Also

this work would gain insight into understanding on the roles of stabilization metho

ds on the economic improvement of IL based biomass processing.