We have investigated the influence of gate bias voltage, applied to one of the two gates of the dual gate (DG) MOSFET, on the threshold voltage for different geometric dimensions, gate materials and drain to source voltage. In our studies we have employed the 2-D numerical device simulator ATLAS to determine the threshold voltage pertaining to DG MOSFETs. It is observed that the gate bias plays an important role in modifying the threshold voltage of DG MOSFETs and the threshold voltage increases with more negative values of gate bias for n-channel DG MOSFETs.