The catalytic conversion of cellulose to glucose at the industrial scale is a sustainable approach to the production of fuels and chemicals. Herein, we report the hydrolysis of cellulose to glucose using an inexpensive carbon catalyst in a continuous slurry process. A carbon catalyst prepared by air oxidation showed the highest activity for cellulose hydrolysis owing to the large number of weakly acidic functional groups. The air-oxidized carbon catalyst hydrolyzed cellulose in a plug-flow slurry reactor after mix-milling to produce soluble beta-1,4-glucans. Further hydrolysis of the beta-1,4-glucans to glucose was achieved using a fixed-bed reactor containing Amberlyst-70 catalyst in series with the slurry reactor to obtain glucose in 59% yield. Another approach was to use dilute H3PO4 for the hydrolysis of the beta-1,4-glucans to glucose with a 70% yield, resulting in a space time yield of glucose of 456 kg m(-3) h(-1). The simple design, short residence time, and high space time yield will enable the scaleup of this process using existing chemical technology.