Structurally well-defined pyrene oligomers were synthesized by reacting 2-tert-alkylpyrene with Cu(BF4)(2)center dot nH(2)O in butyronitrile. It was found that the dimer was formed selectively on treatment with 0.5 equiv of the Cu salt, and no higher oligomers were formed (corrected yield, c.y.: 81%). Even-numbered oligomers were prepared easily by repeated dimerization, i.e., the dimer formed the tetramer (c.y.: 51%) and the tetramer gave the octamer (c.y.: 38%).