We report our numerical studies on microscopic self-organization of a react
ion system in three types of differently connected networks: a regular netw
ork, a small-world network, and a random network. Our simulation results sh
ow that the topology of the network has an important effect on the communic
ation among reaction molecules, and plays an important role in microscopic
self-organization. The correlation length among reacting molecules in a ran
dom or a small-world network is much shorter compared with that in a regula
r one. As a result, it is much easier to obtain microscopic self-organizati
on in a small-world or a random network. We also observed a phase transitio
n from a stochastic state to a synchronized state when we increased the ran
domness of a small-world network.