In this study, formic acid was selected as the catalyst to pretreat corn stover which is also a good substrate for biohydrogen and biogas production. The pretreatment effect and the acidogenic characteristic of hydrolysates were also evaluated. Using corn stover (8.00 g) mixed with 72.00 g of formic acid (2.5%) at temperature 190 degrees C for reaction time 10 min, 17.36 +/- 0.80 g/L glucose, 18.13 +/- 0.83 g/L xylose, 5.45 +/- 0.25 g/L arabinose, 3.88 +/- 0.17 g/L acetic acid, and 1.96 +/- 0.07 g/L furfural were obtained in the hydrolysate. The kinetic parameters of the Saeman model were determined to predict the percentage of xylan remaining in the substrate and the xylose in the liquid. Two kinds of specific hydrolysates (the highest yield of total sugar and highest yield of furfural) in the following acidogenic fermentation experiments were examined. The results indicated that both of the hydrolysates were shown to be butyric acid type fermentation and got the highest VFAs concentration of 6.3 +/- 0.48 g/L. Diluted formic acid had good catalytic effects on the hydrolysis of corn stover. The hydrolysates obtained from the pretreatment process could be used as good substrates for acidogenic fermentation process.