Studies on the mechanism of cobalt biosorption by cobalt-trained Mucor rouxii NRRL 1894 biomass were conducted to determine the environmental conditions that would speed up this process. The rate of CO+2 removal from solution proceeded rapidly and it appeared to be virtually complete during the initial 5 min., and very slowly increased by time until reached to the maximum after 3h. of incubation of the biomass with cobalt solution. This pattern of accumulation was identical in biomass treated with metabolic inhibitors (NaN3 or DNP) or heat-killed biomass. Cobalt removal from solution by the biomass was not affected by the change in temperature (25ºC to 50ºC) and was only affected by reduced temperature (5ºC). The effect of pH was very significant in terms of the potential applicability of recovery since cobalt removal from solutions increased linearly with the increase in pH within the range of pH 1.5 to 6.0. The amount of CO+2 removed increased as the initial concentration increased, and the removal was efficient (80.9%) in solution containing up to 147.8 ppm CO+2, while the uptake capacity increased at 197 ppm CO+2, suggesting a saturation kinetics with respect to CO+2 concentration. The efficiency of sorption of cobalt and zinc dust mixture was that of sorption of cobalt from its pure solution or zinc dust from its pure suspension, on the other hand, the M. rouxii biomass removed 93.36-96.80% of zinc dust. The uptake of cobalt from 42x10-1m eq/l of cobalt solution was not affected by the presence of either Ca+2, Mg+2 or Na+2 (light metal ions) or from a solution containing all these light meal cations.