The formal kinetics of a system of irreversible isokinetic consecutive reactions (i.e. reactions having the same rate and the same rate constants) has been established, considering a common (pseudo-) first order rate constant k. The characteristics of the kinetics of all intermediates have been determined. The nth intermediate goes through a maximum located at time t n m a x = n/k and is equal to (a/n!) (n/e) n , a being the initial number of moles of the reactant. For large values of n (n > 4), this maximum tends to a/√2πn. The selectivity in the nth intermediate has been found equal to ((kt) n - 1 /n!)(n-kt)). Other relationships independent of time with dimensionless parameters correlating the partial conversion τ n of each intermediate product with the total conversion τ of the initial reactant have also been determined. τ n has been found to vary as a function of τ as: τ n = (1-τ)/n![ln(1/(1-τ))] n . The maximum of τ n for the first intermediate tends to 1/e, whereas for higher values of n, this maximum tends to (1/√2πn). A new concept of molecular exposure , expressed in moles second (or in molecules second), has been defined. It corresponds to the surface area comprised between each curve and the x-axis. It has been demonstrated that it remains constant, as well for the reactant as for all the intermediates formed in isokinetic reactions. It is equal to a/k. Some examples from the literature on the catalytic conversion of hydrocarbons such as mono- and dihydrogenations of diolefins and deuterium-alkane isotopic exchange, illustrate and substantiate this kinetic model.