A bench study was carried Out to characterize the kinetics of two plant growth promoting rhizobacteria (PGPR) Azotobacter chroococcum and Bacillus megaterium to adsorb heavy metals from Solution. Adsorption of Ph(2+) and Cd(2+) by bacterial cells was processed quickly with all equilibration achieved within 5 min. The adsorptions were fitted well with Freundlich and Langmuir isotherm models. The comparison of isotherm parameters indicated that A. chroococcum had a stronger capacity to bind metal ions than B. megaterium, with an average increase of 59.8% for Pb(2+) and 75.6% for Cd(2+) respectively. Both bacteria had a stronger affinity to Pb(2+) than Cd(2+) since Pb(2+) was more easily bound with the phosphoryl groups on the cell surface than Cd(2+). This demonstrated that the presence of bacteria in the rhizosphere may result ill the reduction of mobile ions in soil solution. (C) 2009 Elsevier Ltd. All rights reserved.