A high-purity hexadecyl hydrogen maleate (HHM) single crystal of dimensions 60 x 40 x 3 mm(3) can be grown over a period of 1 month using the appropriate method. The solvent used in the growth of the crystal consists of a mixture of benzene and other suitable organic solvents. Diffraction studies on the crystal have indicated the suitability of this system in the dispersing of ultrasoft X-ray in X-ray spectroscopy, larger 2d spacing (5.85 nm), high resolution and reflection properties. The HHM crystal was employed in an X-ray spectrometer to obtain the spectra of diamond at the C K-edge; the results from the experiments clarify the suitability of a HHM single crystal as an ultrasoft X-ray dispersant. (C) 2002 Elsevier Science B.V. All rights reserved.