Abstract. The problem of detecting the homoclinic orbits of an initially straight buckled beam is addressed. Two families of b.c. are identified and investigated in detail. For the first family, the homoclinic orbits belong to a planar invariant manifold, and are easily computed in closed form. For the second family, the manifold is no longer planar, and is detected via the nonlinear normal modes technique by obtaining approximate expressions which are sufficient to highlight the effects of the non-flatness. A hierarchy of reduced order, single degree of freedom, models is determined. These are obtained by taking into account increasing degrees of nonlinearity in the potential energy, which allow for a more and more refined computation of the homoclinic solution. The various models are compared with each other and discussed in detail, and the nonplanarity of the manifold is illustrated through examples.