Compost humic acid-like (cHAL) polymeric matter (MW = 15610), isolated in 12% yield from food and green waste compost, exhibits very good surfactant properties in aqueous solution: i.e., critical micelle concentration (cmc) = 403 mg/L and surface tension at cmc = 36.1 mN/m. Values of cmc are confirmed also by conductivity and phenanthrene solubility measurements. These results, compared with those for other major commercial and research surfactants, propose cHAL as a competitive low-cost biosurfactant.