Comment on “Exact explicit travelling wave solutions for (n+1)-dimensional Klein–Gordon–Zakharov equations” [Chaos, solitons and fractals 34(2007) 867–871]

•The bifurcations of phase portraits of the Klein–Gordon–Zakharov equations are given.•The correct solutions correspond to homoclinic and heteroclinic orbits are given.•Two exact solutions which the previous author fails to note are obtained.

Jibin Li studied “exact explicit travelling wave solutions for (n+1)-dimensional Klein–Gordon–Zakharov equations.” By using the approach of dynamical system, the author claimed that they had obtained five classes of exact explicit travelling wave solutions. However, we checked the results and found two typographical technical errors in the main results. Furthermore, the author fails to note, for a=0,b<0,h∈(0,∞)a=0,b<0,h∈(0,∞) and a<0,b>0,h=0,a<0,b>0,h=0, there is a family of periodic wave solutions and a series of breaking wave solutions, respectively.