The present study has concentrated on finding a new stationary phase in liquid chromatography. To improve the selectivity of monolithic column, a new ionic liquids-based (ILs-based) monolithic column (150 x 4.6 mm i.d.) is synthesized. Characteristic and evaluation of monolithic column are investigated by field emission-scanning electron microscopy (FE-SEM) and determination of caffeine and theophylline in high performance liquid chromatography (HPLC). FE-SEM images show that this monolithic column has a porosity structure. At the condition of mobile phase was 0.06 mol L-1 Na2HPO4 (pH 9.0) and flow rate was 0.7 mL min(-1), a good linear relationship was demonstrated when the concentrations of caffeine and theophylline were in the range of 0.1-60.0 mu g mL(-1). These two compounds can obtain better resolution on the ILs-based monolithic column than non-ILs monolithic column, and the recoveries ranged from 97.40% to 108.00% and the interday and intraday relative standard deviations were less than 5%. The HPLC method, developed in this study, was proved to be acceptable for drugs assay, and this ILs-based monolithic column as the stationary phase was a potential tool for future HPLC separation. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: 3425-3430, 2010