Two kinds of ion-exchange resins (IERs) with macropores, namely D151 containing -COOH groups and D401 having -NH(CH2COOH)(2) groups, are used as microreactors to synthesize Cu2O. These groups provide the bonding sites for Cu2+, and the macropores act as microcontainers for the reaction and confine the growth of Cu2O crystals within the pore dimensions. The final product, Cu2O-IER composites, can be easily separated from the reaction mixture. This facile and cost-effective strategy would show its merits for large-scale preparation.