Cu(II) immobilized on aminated epichlorohydrin activated silica (CAES) is a novel and efficient heterogeneous nanocatalyst in the [3 + 2] cycloaddition reactions of various organic nitriles with sodium azide. The protocol can provide a series of 5-substituted-1H-tetrazoles under mild conditions in DMSO. Efficient transformation, mild reaction conditions, easy product isolation and the potential reusability of the catalyst are attractive features. The catalyst (CAES) was characterized by FT-IR, TGA, TEM, BET, SEM-EDS, CHN and ICP techniques.