In this article we apply input/output (I/O) renormalization to linear
transport phenomena on fractals. We focus mainly on first-order reacti
on kinetics, on sorption dynamics and on renormalization of integral q
uantities in the case of finitely ramified structures. Moreover, care
is taken to show how the theory can be extended to the study of infini
tely ramified fractals and non-linear models and to the case of an unb
ounded number of input sites.