Groundwater pollution by Non-Aqueous Phase Liquids (NAPLs) has become an increasing threat. This article studied the steam injection efficiency in the groundwater remediation contaminated with non-aqueous phase liquid (diesel) through a bench-scale laboratory experiment. The experimental set up consists of a steam boiler and sandbox. Steam, which was generated from the steam boiler was supplied to the sandbox at injection rate of 0.14m3/s, pressure of 1.5bar and temperature of 150°C. The initial volume of diesel used was 500ml. At the supply of the steam to the sandbox, it was observed that the mixture of groundwater and diesel was heated and at a temperature above their boiling points, the mixture change phase and vaporized from the chamber through the outlet or recovery side into the condenser and were separated on cooling using phase separator. The remediation time was from 0 to 6 hours and it was showed that as the time increases, the recovered volume of diesel increases as 66.04% of diesel was recovered after the allowed 6hours. Therefore, it was evident that the steam injection technique is efficient in the removal of light non-aqueous phase liquids in groundwater.