The polarographic behaviour of trans azodioxycyclohexane and trans α,α'-azodioxytoluene has been investigated in ethanol-water solutions. In acid medium, a preprotonation of the molecule and the cleavage of an oxygen are first observed, leading to the corresponding azoxy compound (2 electron step). A second reduction step leads to the hydrazo compound through the intermediate azo compound (4 electron step). In neutral medium, a single 6 electron reduction wave is observed. The neutral molecule is reduced in alkaline medium; an unstable intermediate is formed which dehydrates very fast into cis and trans azoxy compounds. In the case of trans α,α'-azodioxytoluene, both cis and trans azoxy compounds are reduced to α,α'-hydrazotoluene which is the final reduction product. In the case of trans azodioxycyclohexane, the corresponding trans azoxy compound is no longer reducible and a mixture of azo, hydrazo and trans azoxy compounds is obtained.