Sustainable new insights into the development of Co3O4 as a natural litigation agent via cobalt-ellagate complex formation were revealed using Nephelium lappaceum L. peel-waste resources. Suggestive cell (3T3) suffering was more obvious at 500 μg ml-1 Co3O4 dosages, with a decrease in cell viability of ∼30%. This material is a potentially suitable candidate for applications in biomedicine and sustainable materials development. © 2014 the Partner Organisations.