This is the first study showing pH dependence of three distinct redox sites within bilirubin oxidase (BOD) adsorbed on a nanocomposite modified electrode. The 1st redox centre with the highest redox potential E c(1st) =404mV vs. Ag/AgCl (614mV vs. NHE at pH7.0) exhibited pH dependence with a slope -dE c(1st) /dpH=66(±3) mV under a non-turnover process. The 2nd redox centre with a potential E c(2nd) =228mV vs. Ag/AgCl (438mV vs. NHE at pH7.0) was not dependent on pH in the absence and presence of O 2 . Finally, the 3rd redox site with a redox potential E c(3rd) =92mV vs. Ag/AgCl (302mV vs. NHE at pH7.0) exhibited pH dependence for a cathodic process with -dE c(3rd) /dpH=70(±6) mV and for anodic process with -dE a(3rd) /dpH=73(±2) mV, respectively. Moreover, two break points for dependence of E c(1st) or E c(3rd) on pH were observed for the 1st (T1) site and the 3rd site assigned to involvement of two acidic amino acids (Asp105 and Glu463). A diagram of a potential difference between cathodic peaks of BOD as a dependence on pH is shown. The results obtained can be of interest for construction of biofuel cells based on BOD such as for generation of a low level of electricity from body fluids.