Abstract The objective of this paper is to investigate the equation of motion of circular cylinder. The dissertation is done by considering two dimensional irrotational flow over a circular cylinder using potential and stream functions. It includes the cases where the cylinder is moving in the liquid at rest at infinity, the flow past a fixed circular cylinder, and streaming and circulation about circular cylinder. Equations which represent such motions are derived. The motion of two coaxial cylinders, the space between them is filled with liquid, is also expressed using potential and steam functions.