We performed the transient kinetics of the oxidation reaction between DsbA(SH,SH) and DsbB(S-S,S-S) embedded in supported lipid bilayers immobilized on a 27-MHz quartz-crystal microbalance, under various pH conditions, in order to investigate the pH-adaptability mechanism of the Dsb system. The obtained kinetic parameters indicated that two pairs of cysteine residues in DsbB(S-S,S-S) were important for both the stability of the DsbA-DsbB intermediate and the oxidation of DsbA over a wide pH range.