SUMMARYAn e cient numerical method is developed for the numerical solution of non-linear wave equations typiÿed by the regularized long wave equation (RLW) and its generalization (GRLW). The method developed uses a pseudo-spectral (Fourier transform) treatment of the space dependence together with a linearized implicit scheme in time.An important advantage to be gained from the use of this method, is the ability to vary the mesh length, thereby reducing the computational time. Using a linearized stability analysis, it is shown that the proposed method is unconditionally stable. The method is second order in time and all-order in space.The method presented here is for the RLW equation and its generalized form, but it can be implemented to a broad class of non-linear long wave equations (Equation (2)), with obvious changes in the various formulae.Test problems, including the simulation of a single soliton and interaction of solitary waves, are used to validate the method, which is found to be accurate and e cient. The three invariants of the motion are evaluated to determine the conservation properties of the algorithm.