In order to develop a high-performance biosorbent for Ru biosorption from Ru-containing acetic acid wastewater, decarboxylated polyethylenimine (PEI)-modified bacterial biomass (DC-PEIB) was prepared through the PEI coating and esterification of carboxyl groups on the biomass surface. The raw biomass (RB) and PEI-modified biomass (PEIB) were also prepared for comparison with DC-PEIB. To confirm the surface modification, SEM and FTIR analyses were carried out and their results revealed that the DC-PEIB was well prepared according to the suggested modification method. The sorption kinetics showed that sorption equilibrium was reached within 60 min. According to the Langmuir model, the maximum uptake of the DC-PEIB was estimated to be 47.1 mg/g. Whereas those of RB, PEIB and PEI-Silica gel were 25.0, 34.4 and 11.4 mg/g, respectively. Therefore, esterification of the carboxyl groups on the PEIB surface led to further enhancement of the Ru sorption capacity. (C) 2013 Elsevier B.V. All rights reserved.