Although electrodeposition of chromium has been practiced for 75 years
, the mechanism is still open to conjecture. Part of the reason is the
complexity of the chemistry of chromic acid and its existence in aque
ous solution in the form of coordinated octahedral complexes, These co
mplexes vary both structurally and kinetically at different CrO3 conce
ntrations. The chemistry of tri- and hexavalent chromium is discussed,
including polymerization and related mechanisms relative to the overa
ll deposition mechanism.