In this paper, the quintic B–spline method is employed to calculatenumerical solution of the initial-boundary value problem of Rosenau–Burgersequation. This scheme is based on the Crank–Nicolson formulation for time integration and quintic B–spline functions for space integration. The unconditional stability of the method is proved using Von–Neumann approach. A priori bound and the error estimates of the approximate solutions are discussed with a numerical example.