A simple and highly sensitive CE-UV method was applied in the determination of l-ctrulline, which was developed from an oral formulation for pediatric use. The novel method was based on the analysis of l-citrulline for direct ultraviolet detection at 198 nm. The BGE consisted of 10 mM sodium tetraborate and 50 mM SDS at pH 9, and the electrophoretic parameters were optimized. The method was validated in terms of specificity, linearity, LOD, LOQ, precision, accuracy, and robustness. The LOD and LOQ obtained were 1.36 and 4.54 mu g/mL, respectively. In addition, the method offers higher sensitivity and specificity compared with the results obtained from HPLC method using UV-detectors, in which l-citrulline needs to be derivatizated. Furthermore, low cost and simplicity of the system allowed the rapid and simple quantitation of l-citrulline in the oral formulation for quality control and stability indicated method.