In this research work process parameters and breakthrough modeling of thorium biosorption on orange peel in a fixed-bed column has been studied. Some experiments have been done with sorbent diameter, flow rate, bed height and feed inlet concentration. Breakthrough point decreased with decreasing the bed height, increasing feed inlet concentration and increasing flow rate. Meanwhile, sorption capacity increased with decreasing bed height and flow rate. The highest sorption capacity, 87.7 mg/g, occurred in a 0.4–0.8 mm sorbent diameter. The experimental results were fitted by models of Thomas, Yoon–Nelson and Modified Dose–Response (MDR). The MDR model showed better results.