A reliable, sensitive, and rapid coulometric titration (CT) method was developed for the purity determination of luteolin reference material candidates. The results obtained from the proposed CT method were compared with those obtained from differential scanning calorimetry (DSC) and mass balance method. The performance of the CT method was comparable, and the quantitative results of the proposed methods were in good agreement with those of DSC and mass balance methods. CT has the advantages of minimal sample requirement, rapid measurement, high accuracy, good reproducibility, and no corresponding reference standard requirement. This method can be used for luteolin purity assays and related production quality control.