The growth of holmium tartrate trihydrate (HTT) single crystals is achieved in organic (agar-agar) as well as in inorganic (silica) gels by single gel diffusion method. Results of the study on nucleation kinetics of crystals grown in silica gel are described. The crystals exhibit the morphological form of a tetragonal dipyramidal class with { 0 0 1} and {111} as dominant faces. Elemental and thermogravimetric analysis (TGA) supplemented by energy dispersive analysis of X-rays (EDAX) support the suggested chemical formula of the grown crystals to be [Ho (C4H4O6) (C4H5O6)(.)3H(2)O]. Single crystal X-ray diffraction (XRD) studies indicate that the crystals belong to tetragonal system with the cell parameters a = 5.97 angstrom, c = 36.09 angstrom, bearing the space group P4(1). Fourier transform infrared (FT-IR) spectroscopic study indicates the presence of tartrate ligands and suggests that one of the tartrate ions is singly ionized. TGA suggests that the material is thermally stable up to 220 degrees C. (c) 2007 Elsevier B.V. All rights reserved.