A bioflocculant - producing bacterium was isolated from water samples collected from the Vaigai river and was identified as Klebsiella sp. by morphological and biochemical characteristics. Chemical analysis of the purified bioflocculant indicated that it was a sugar-protein derivative, composed of sugar (76.83%, w/w) and protein (23.17%, w/w). Infrared spectrophotometry revealed that the bioflocculant contains carboxyl, hydroxyl and amino groups as structural components. Scanning electron microscopy (SEM) of the purified bioflocculant showed that it has an irregular, coarse-grained structure connected in netted textures. The concentration of bioflocculant produced after 48 h of cultivation was 0.73 g/L. At the optimal concentration, the bioflocculant caused 91.28% more settling of kaolin than the control in 5 min.