The equation $y^2-k=x^3$ has only a finite number of solutions for a given k. In the present thesis, after we reduce the given equation to the finite number of the Thue equations, we refine some techniques of Ellison, Petho and Steiner and show that the only integer solution of the equation $y^2+127=x^3, y$ positive, is $x=16, y=63$.