Bifurcation structure of the hydrogen peroxide-sulfite system was examined quantitatively under the flow condition, from which rate constants k(2) and k(3) and equilibrium constant K-1 for the skeleton reactions H+ + SO32- <-> HSO3- (1); HSO3- + H2O2 --> H+ + SO42- + H2O (2); and H+ + HSO3- + H2O2 --> 2H(+) + SO42- H2O (3) were determined at 13.2, 20.0, 25.0, and 32.0 degrees C. The results are summarized as k(2) (M(-1)s(-1)) = (1.19 x 10(6))exp(-Delta H(2)double dagger/RT), Delta H(2)double dagger = 28.2 kJ.M-1; k(3) (M(-2)s(-1)) = (5.93 x 10(9))exp(-Delta H(3)double dagger/RT), Delta H(3)double dagger = 18.7 kJ.M-1; K-1 (M-1) = (1.8 x 10(6))exp(-Delta H-1/RT), Delta H-1 = 7.4 kJ.M-1. The system is well known to exhibit chemical oscillations in its pH value when it is combined with an appropriate species that provides a negative feedback channel. However, the role of the nonlinearity inherent in this subsystem has not been clarified sufficiently under the flow condition. In the present work, we proposed an approximate analytical method to analyze the complicated equations representing the bifurcation structure and succeeded in determining the above constants and their temperature dependence. The present results are expected to be useful in designing a new chemical oscillator system by coupling this subsystem with appropriate negative-feedback species. In addition, the information given here for the temperature dependence would be useful to design the temperature-insensitive chemical oscillator system which is interested recently in relation to the function in living systems.