Inherently nanostructured CPx compounds were studied by first-principles calculations. Geometry optimizations and cohesive energy comparisons show stability for C3P, C2P, C3P2, CP, and P-4(P-2) species in isolated form as well as incorporated in graphene layers. The energy cost for structural defects, arising from the substitution of C for P and intercalation of P atoms in graphene, was also evaluated. We find a larger curvature of the graphene sheets and a higher density of cross-linkage sites in comparison to fullerene-like (FL) CNx, which is explained by differences in the bonding between P and N. Thus, the computational results extend the scope of fullerene-like thin film materials with FL-CPx and provide insights for its structural properties. (c) 2006 Elsevier B.V. All rights reserved.