In this paper, the authors present to design of 32-bit Arithmetic and Logic Unit (ALU) by taking the advantage of concept called Gate Diffusion Input (GDI) technique. ALU is the important block to design the embedded and microprocessors. The arithmetic unit will do the arithmetic operations, as addition and subtraction. The logic unit will do the logic operations as AND, OR, XOR and XNOR by using the concept GDI technique. The simulation results were taken using the digital schematic tool in 120nm technology.