Corynebacterium glutamicum was prepared for the sorption of Reactive Red 4 (RR 4) and Methylene Blue (MB). The pH edge experiments showed that the pH of the solution was an important controlling parameter. An increased salt concentration strongly influenced the uptake of MB, but had no effect on RR 4. In order to identify the binding sites for the dye molecules, the biosorbent was potentiometrically titrated. The result showed that four types of major functional groups were present on the surface of biomass, which was confirmed by FTIR analysis. It was found that NH3 were likely to be the binding sites for anionic RR 4, and -COO played a role in electrostatic attraction with cationic MB.