Adiabatic logic has been found to be effective in achieving low power in VLSI circuits. In subthreshold region, the circuit conducts a small current and consumes lesser power. In this paper, the dual rail power supply with 0 and 180°phase difference has been used for subthreshold adiabatic logic (SAL). A priority encoder is designed using SAL with dual rail power supply. All the circuit simulations are done using HSPICE simulator at 22 nm PTM technology. In-phase dual supply offers low power consumption, whereas out-phase dual power supply offers an improved noise margin.