The pollution of phosphate has been regarded as a serious global environmental issue in the past decade. In this study, mesoporous feroxyhyte (delta-FeOOH) nanoparticles were synthesized and delta-FeOOH/Fe(II) system was employed for the removal of phosphate. Effect of initial pH as well as conversion of Fe(II)/Fe(III) in solution were investigated. Brunauer-Emmett-Teller analysis, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were employed to characterize the delta-FeOOH nanoparticles before and after reaction in order to reveal the possible mechanism. Results indicated that delta-FeOOH/Fe(II) system showed a great removal performance (94.1%) for phosphate under acidic condition and the removal of phosphate by delta-FeOOH/Fe(II) system was a process which simultaneously included adsorption and chemical precipitation. Phosphate removal by delta-FeOOH/Fe(II) system was endothermic, spontaneous and followed the Freundlich isotherm model and pseudo-second-order model. The great phosphate removal capability of the delta-FeOOH/Fe(II) system exhibited its potential as an effective method for phosphate immobilization in wastewater. (C) 2019 Elsevier B.V. All rights reserved.