The molecular structure of the 5,10,15,20-tetra(1-naphthyl)porphyrin and 5,10-di(4-hexadecyloxyphenyl)-15,20-di(4-pyridyl)porphyrin were studied using high-energy X-ray diffraction (ID 15-B beam line) at ESRF, Grenoble, France. The energy of the incident photons was 90.45 keV. Two-dimensional detector was used. The intensity data were converted to the pair correlation function via the Fourier transform. The theoretical pair correlation functions were simulated using the density functional theory and compared with the experimental data. Obtained results indicate that the used experimental technique together with the applied interpretation method can be regarded as efficient tools for the determination of the atomic arrangement in molecules of such kind. (C) 2007 Elsevier B.V. All rights reserved.