The influence of temperature on the bioleaching of iron from silica sand with Aspergillus niger has been studied with three size fractions of silica sand: +120-212µm, +212-300µm, and +300-425µm over the temperature range 40 to 800C for several hours. The experimental data were fitted to the shrinking core model (ash layer diffusion control and chemical reaction control) and a mixed kinetic model that incorporates a multiplying factor, b. Optimal temperature for bioleaching was found to be 700C and the amount of iron leached increased with decreasing particle size, with +120- 212µm being the most effective particle size fraction. The shrinking core model with chemical reaction control and ash layer diffusion control failed to explain the effect of temperature on the kinetics of bioleaching. The mixed kinetic model with the multiplying factor b=0.2 gave a perfect fit to the experimental data after the second hour of bioleaching. At the early part of the bioleaching process where the mixed kinetic model failed, ash layer diffusion seemed to be in control. Based on our work, a staged bioreactor design that relies on the ash layer and mixed kinetics models may be required for the process.