This work aimed to investigate the remediation performance and reaction behavior of the injection of nanoscale Fe3O4 slurry coupled with the electrokinetic (EK) process for remediation of NO3- in a saturated soil with the texture of sandy clay. First, 0.8 wt% of polyacrylic acid (PAA) was added to the laboratory-prepared nanoscale Fe3O4 to yield the nanoscale Fe3O4 slurry. Thus prepared slurry was then injected into the anode reservoir of the EK set-up for remediation of nitrate-contaminated soil ([NO3-] = 69.39-71.65 mg/kg) in the soil compartment (L: 25 cm; Phi: 10 cm). Application of an electric field of 1 V/cm and daily injection of nanoscale Fe3O4 slurry at a dose of 5 g/L were practiced during the test period of 12 d. The remediation results indicated that residual NO3--N concentration of 1.35 mg/L in the anode reservoir was found to be lower than Taiwan EPA's Pollution Control Standards for Type I Groundwater Quality. In addition, a very low residual NO3- concentration in soil was detected. It indicates that the hybrid technology employed in this work is effective for remediation of nitrate in the subsurface following the adsorptive reduction model. The relevant reaction behavior was discussed. (C) 2011 Elsevier B.V. All rights reserved.