The oxidative coupling of primary aromatic amines was investigated. Ce(SO4)2 can mediate the oxidative coupling of primary aromatic amines in water to dimers, trimers and/or tetramers, which depended on the substituents of primary aromatic amines. When 2,6-dimethylaniline or 2,6-diethylaniline was used as substrate, dimer, and tetramer were formed as major products. When 2,6-diisopropylaniline or 2,6-dihaloanilines was used as substrate, dimer, and trimer were formed. The mechanistic aspect was also investigated. The oxidative coupling of primary aromatic amines was investigated. Ce (SO4) 2 can mediate the oxidative coupling of primary aromatic amines in water to dimers, trimers and / or tetramers, which depended on the arrangements of primary aromatic amines. When 2,6- dimethylaniline or 2,6-diethylaniline was used as a substrate, dimer, and tetramer were formed as major products. When 2,6-diisopropylaniline or 2,6-dihaloanilines was used as a substrate, dimer, and trimer were formed. The mechanistic aspect was also investigated.