Abstract A very safe and environmentally friendly solid- state material for bioremediation was prepared using a combination of Aspergillus oryzae and poly(e-caprolac- tone) (PCL), a porous biodegradable polymer. The novel material was capable of decomposing 200 ppm formalde- hyde solutions to 0 ppm within 7 days. Degradation ability was prolonged by addition of yeast extract-peptone-dex- trose medium into the composite; 200 ppm formaldehyde was decomposed to 0 ppm over eight additional decom- position cycles and 100 days. A unique mechanism is proposed where, during PCL degradation, the solid-state composite provides nutrients to A. oryzae.