An adsorbent prepared from fluid catalytic cracking (FCC) spent catalyst fines and diatomite, and its adsorption of Cu2+, Zn2+, and Ni2+ ions were investigated. The adsorbent was characterized by XRD, SEM, and N2 adsorption-desorption techniques. The results showed that the specific surface area and pore volume of adsorbent increased with the increase in FCC spent catalyst fines. The influence factors on the adsorption of the adsorbents were studied. The suitable adsorption conditions were: pH value of 5.0, ratio of solid to liquid of 1 : 600 (g:ml), adsorption time of 4 h, room temperature. The adsorption of metal ions varied with the type of metal cations. The adsorption isotherms suggested that the sequence of the adsorption efficiency was Cu2+ >Zn2+ >Ni2+. The amount of Cu2+, Zn2+, and Ni2+ metal ion adsorbed onto the adsorbent was 49.17 mg g–1, 46.83 mg g–1, and 35.72 mg g–1, respectively. The adsorption data of Cu2+, Zn2+, and Ni2+ ions fitted well with the Freundlich adsorption isotherm model.; Ispitivan je adsorbens pripremljen iz katalizatora za katalitičko krekiranje u vrtložnom sloju (FCC) i diatomita, te njegova adsorpcija iona Cu2+, Zn2+ i Ni2+. Adsorbens je karakteriziran XRD, SEM i N2adsorpcijsko-desorpcijskim tehnikama. Rezultati su pokazali da se specifična površina i volumen pora adsorbensa povećavaju s povećanjem količine potrošenog katalizatora FCC. Proučavani su čimbenici utjecaja na adsorpciju adsorbensa. Prikladni uvjeti adsorpcije bili su: pH vrijednost 5,0, omjer čvrste tvari i kapljevine 1 : 600 (g:ml), vrijeme adsorpcije 4 h i sobna temperatura. Adsorpcija metalnih iona varira s tipom metalnih kationa. Adsorpcijske izoterme pokazale su da je slijed učinkovitosti adsorpcije Cu2+ >Zn2+>Ni2+. Količina metalnih iona Cu2+, Zn2+ i Ni2+ adsorbiranih na adsorbensu iznosila je 49,17 mg g–1, 46,83 mg g–1, odnosno 35,72 mg g–1. Podatci o adsorpciji iona Cu2+, Zn2+ i Ni2+ slijede model Freundlichove adsorpcijske izoterme.