A method based on high-performance liquid chromatography (HPLC) with ultraviolet detection has been developed to quantify coenzyme Q10 (CoQ10) in raw materials and dietary supplements. Single-laboratory validation has been performed on the method to determine linearity, selectivity, accuracy, limits of quantification (LOQ) and repeatability for CoQ10. An excellent linearity (r = 0.999) was observed for CoQ10 in the concentration range 15.625~500 μg/mL in dietary supplement. Observed recovery of CoQ10 was found to be between 98.33 and 99.38%. LOQ was found to be 250 μg/mL Repeatability precision for CoQ10 was between 0.15 and 0.21% relative standard deviation (RSD). Further, limited studies showed that some adulterants and degraded material could be satisfactorily separated from CoQ10 and identified.