For the first time, successive reactions was used in differential kinetic analysis, and simultaneous determination of epinephrine and norepinephrine based on it was carried out. For successive reaction A^k^1→B^k^2→C, because the integral kinetic equation have relationship with two rate constants K1 and K2, two rate constants can be used in differential kinetic analysis, this afford more possibility to increase the kinetic difference between mixed species. The successive reaction between tris (1,10-phenanthroline)-iron(III) and epinephrine or norepinephrine was investigated, it was found that between the two species, k1 was similar, but k2 had enough difference, this was exploited by conventional proportional-equation method to resolution of epinrphrine-norepine-phrine mixture at the 10^-^5 mol.dm^-^3 level over the ratio range 1:6.88-2.91:1, with an error of less than ±5% and an average precision of about 2.5%.

Key words: IRON COMPLEX, SIMULTANEOUS DETERMINATIONS, PHENANTHROLINE, EPINEPHRINE, NOREPINEPHRINE, RATE DIFFERENTIAL KINETICS, CONSECUTIVE REACTION