The structure of single-wall carbon nanohorns has been studied using pulsed neutron diffraction and molecular dynamics. The collected diffraction data have been converted to a real-space representation in the form of the pair correlation function. For computer-generated models consisting of nanocones and single-wall carbon nanotubes of the perfect hexagonal structure and 20-30 angstrom in diameter, the computed diffracted intensities and pair correlation functions are in reasonable agreement with the experimental data. For larger nanohorns of 50 angstrom diameter, Stone-Wales, mono-vacancy and di-vacancy defects have been introduced to fit the experimental data. (C) 2010 Elsevier B.V. All rights reserved.