The complexation of copper was studied in rainwater collected in Norwich, UK, and during Atlantic and Indian Ocean cruises. The complexation was measured with Chelex resin, Sep-Pak columns and adsorptive cathodic stripping voltammetry with tropolone as a competing ligand. Strong organic complexation was observed in semi-urban and marine rain samples with conditional stability constants between 1011 and 1014. Model solutions of copper and humic matter found organic complexes of a similar strength to those observed in the rain samples suggesting humic material as a potential ligand. A large proportion of the copper in the rains was associated with strong organic complexes over the pH range 4-8 in both filtered and unfiltered rain samples suggesting organic complexation is an important process both in the atmosphere and on arrival to oceans.