M. Ghasemi - Department of Applied Mathematics, Faculty of Science, Shahrekord University, Shahrekord, P. O. Box ۱۱۵, Iran.
A. Azizi - Department of Mathematics, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran.
M. Fardi - Department of Mathematics, Islamic Azad University, Boroujen Branch, Boroujen, Iran.

In this paper, an application of homotopy perturbation method is appliedto nding the solutions of the seven-order Sawada-Kotera (sSK) and a Lax'sseven-order KdV (LsKdV) equations. Then obtain the exact solitary-wave so-lutions and numerical solutions of the sSK and LsKdV equations for the initialconditions. The numerical solutions are compared with the known analyticalsolutions. Their remarkable accuracy are nally demonstrated for the bothseven-order equations.