Carboxylated PIM-1 fibers were prepared by one-step hydrolysis of PIM-1 fibers using sodium hydroxide solution. The chemical structure and morphology of the hydrolyzed PIM-1 fibers were characterized. The adsorption behaviors of the hydrolyzed PIM-1 fibers towards different organic dyes and heavy metal ions in an aqueous solution were investigated. The results showed that the hydrolyzed PIM-1 fibers could effectively adsorb methylene blue (MB), safranin O (SO), and methylene violet (MV), but barely adsorb methyl orange (MO), indicating a selective adsorption property. Isotherm studies revealed that the Freundlich model was more suitable for describing the adsorption behavior of the hydrolyzed PIM-1 fibers than the Langmuir model. The adsorption mechanism was investigated by UV-vis absorbance spectra and solution pH effect. It was concluded that the adsorption process was based on the host-guest interactions between the hydrolyzed PIM-1 fibers and the dyes. In addition, the hydrolyzed PIM-1 fibers exhibited an improved adsorption capacity for heavy metal ions (41.2 mg/g for Pb2+, 16.9 mg/g for Cu2+, respectively) than the pristine PIM-1 fibers. Based on our results, the hydrolyzed PIM-1 fibers, as an easily prepared adsorbent material, show potential application for the selective removal of various organic dyes and heavy metal ions in wastewater treatment. (c) 2016 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.