A new chitosan molecular-imprinted adsorbent was prepared from the mycelium of waste biomass. The results showed that an adsorbent using Penicillium chrysogenum mycelium as the core material was better than one derived from peanut coat. The adsorption capacity of the surface-imprinted adsorbent for Ni2+ was enhanced by increasing the chitosan concentration in the imprinting process. Epichlorohydrin was better than glutaraldehyde as a cross-linking agent; the optimal imprinted Ni2+ concentration for preparing the surface-imprinted adsorbent was 2 mg (Ni2+) g(-1) of mycelium. The adsorption capacity of the surface-imprinted adsorbent was 42 mg g(-1) (at 200 mg dm(-3) initial metal ions concentration) and twice that of the mycelium adsorbent. The surface-imprinted adsorbent can be reused for up to 15 cycles without loss of adsorption capacity. (c) 2005 Society of Chemical Industry.