and a mohebbi@kashanu.ac.ir Z. Naturforsch. 66a, 735 -744 (2011) / DOI: 10.5560/ZNA.2011-0038 Received April 13, 2011 / revised July 6, 2011 In this work we propose fast and high accuracy numerical methods for the solution of the onedimensional nonlinear Klein-Gordon (KG) equations. These methods are based on applying fourthorder time-stepping schemes in combination with discrete Fourier transform to numerically solve the KG equations. After transforming each equation to a system of ordinary differential equations, the linear operator is not diagonal, but we can implement the methods such as for the diagonal case which reduces the time in the central processing unit (CPU). In addition, the conservation of energy in KG equations is investigated. Numerical results obtained from solving several problems possessing periodic, single, and breather-soliton waves show the high efficiency and accuracy of the mentioned methods.