Abstract: The invention is a composition for use in deactivating iron species in hydrocarbon fluids, comprising the products resulting from the reaction of (I), with (II) and (III) is disclosed; wherein (I) is a substituted catechol of the structure ##STR1## where R is chosen from alkyl, aryl, alkaryl, or arylalkyl from about 1 to 20 carbon atoms; wherein (II) is a mixture of polyamines having the repeat structure ##STR2## wherein m ranges from 1 to 10 and where X is an alkyl, branched alkyl, cyclic or branched cyclic alkyl of from 1 to 10 carbon atoms, and where Y is a substituted alkylphenol of structure ##STR3## where R" is chosen from alkyl, aryl, alkaryl, arylalkyl of from about 1 to 22 carbon atoms; wherein (III) is an aldehyde of structure ##STR4## where R' is chosen from hydrogen, and an alkyl of from 1 to 6 carbon atoms. Also disclosed is the function of the said same composition, resulting from the reaction of (I) with (II) and (III), as an antioxidant in hydrocarbon fluids.