A sensitive and selective electrochemical method was developed for simultaneous determination of uric acid and xanthine using the nano boron doped ceria modified glassy carbon paste electrode (nano-B-CeO2/GCPE). The proposed sensor exhibited an excellent catalytic activity, high sensitivity and good selectivity toward the oxidation of uric acid and xanthine. The potential mutual interference of uric acid (UA), xanthine (XA), dopamine. (DA) and ascorbic acid (AA) were examined indicting that their oxidation take place independently at the nano-B-CeO2/GCPE sensor. For simultaneous detection by synchronous change of the concentration of UA and XA, the linear ranges were 0.42-11.87 mu M and 0.07-2.02 mu M with detection limits of 5.39 x 10(-9) M and 236 x 10(-9) M, respectively. The proposed method was successfully applied to simultaneous determination of UA and XA in human urine and serum samples with satisfactory results. (C) 2016 Elsevier B.V. All rights reserved.