In this study, a monolithic organic polymer stationary phase was modified using 18-crown-6-ether for use in capillary ion chromatography. Its use in the separation of inorganic anions was investigated. The monolithic stationary phase was obtained by chemically bonding 2-aminomethyl-18-crown-6-ether to a polymer skeleton comprising glycidyl methacrylate and ethylene glycol dimethacrylate. The optimum level of loading of 2-aminomethyl-18-crown-6-ether onto the stationary phase was investigated. The resulted stationary phase was used to investigate the influence of the eluent cation, the concentration of the eluent, and the pH of the eluent on the separation of inorganic anions.