Many redox reactions in the natural environment proceed too slowly to approach their equilibrium state, absent the action of catalysts or enzymes. In this chapter, we consider how to trace multicomponent reaction paths in which the progress of redox reactions is described by kinetic rate laws. We frame our discussion in terms of three example calculations. In the first example, ferrous iron both catalyzes and provides reducing power to convert uranyl to insoluble uranium hydroxide. The autocatalysis of manganese, in which the reaction product operates as the catalyst that promotes the reaction, serves as the second example, and the microbial degradation of phenol makes up the final illustration of the method.