A novel electrocatalytic platform based on 5,15-bis (p-amino)-tetraphenylporphyrin (BATPP)/α-Al₂O₃ composites (sensitive materials) coated on glassy carbon electrodes, which was constructed by a simple electrochemical method, is reported. The directly simultaneous electrocatalytic oxidation and selective voltammetric peak separation of a mixture including ascorbic acid (AA), dopamine (DA) and uric acid (UA) in a phosphate buffer solution was investigated. The results showed that the platform resolved the overlapping voltammetric responses of AA, DA and UA with potential differences of 136 mV (AA to DA), 143 mV (DA to UA) and 279 mV (AA and UA) for cyclic voltammetry (CV). These results will open new opportunities for the development of an electrochemical sensor for the simultaneous determination of DA, UA and AA in real sample analyses in future.