The polarographic reduction of a series of p‐substituted benzyl bromides has been followed in methanol. The half wave potential is found to increase with the introduction of electron releasing and electron attracting substituents, in a manner similar to the rate of nucleophilic substitution. The reduction process is therefore interpreted in terms of a nucleophilic displacement on the saturated carbon atom, with the electron on the mercury cathode as the nucleophilic reagent, followed by dimerisation of the radical formed. This radical mechanism is supported by the isolation of (p‐NO2C6H4CH2)2from p‐nitrobenzyl bromide, which also shows that the C‐Br bond is attacked more readily than the