The t(0.6) rate law by van den Ende et al. (Radiat. Phys. Chem. 22, 55 1984
) is one of several methods to describe the kinetics of geminate ion recomb
ination. Due to its simplicity it is a very powerful tool to study geminate
ion mechanisms. Complications occur if geminate ions react or fragment. Th
e corresponding theory is given to include one additional ionic reaction an
d two parallel or two consecutive ionic reactions. The theory is applied to
pulse radiolysis results in methylcyclohexane to illustrate the power of t
he method.