Cyclen tetrahydrochloride is a macrocycle hydrochloride salt. It can be synthesized using perhydro-2a,4a,6a,8a-tetraazacyclopenteno[1,3-f,g]acenaphthylene as a precursor. Cyclen tetrahydrochloride has an orthorhombic crystal structure. Cations are reported to exhibit crystallographic two-fold rotation symmetry and [3333] quadrangular conformation, having protonated N atoms at corner positions. Synthesis of cyclen from the corresponding butanedione-protected linear tetramines has been reported.

Cyclen tetrahydrochloride may be used for the synthesis of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methyleneethylphosphinic acid), a new macrocyclic polyaza polyphosphinate ligand. It may also be used in the synthesis of anthraquinone-pendant cyclen.