In this study, Fe-impregnated granular activated carbon (Fe-GAC) were prepared through the hydrolysis of ferrous sulfate on granular activated carbon (Fe-GAC) by the Fe(II)–H2O2 or Fe(II)–O2 (air) method at different temperatures. SEM, BET, XRD, XPS and FTIR characterizations revealed that Fe-GAC through Fe(II)–H2O2 method with a reaction time of 24h resulted in more nanoscale iron hydroxide sulfate hydrate(Fe2S2O9!xH2O), whereas Fe-GAC through Fe(II)–O2 method formed nanoscale iron hydroxide sulfate hydrate with Fe2+. The impregnated iron through the Fe(II)–H2O2 method was more efficiently used for arsenate removal, and the material obtained with a reaction time of 24h was most effective, indicating Fe2+ in Fe-GAC by Fe(II)–O2 method and uneven and clustered iron hydroxide sulfate hydrate at 300–500°C resulted in the low iron efficiency. The arsenate adsorption capacity of Fe-GAC increased linearly with the iron content in the composite material (R2>0.94). The presence of Cl−, SO42−, NO3−, ClO4−, and PO43 – displayed various degrees of inhibitive effect on the adsorption of arsenate, but BrO3− promoted the adsorption of arsenate. The new preparation method and the material provide a useful alternative for improved removal of arsenate from contaminated water.