We have investigated the size-dependent high pressure behavior of nanocrystalline TiN using an angle-dispersive X-ray diffraction technique in a diamond-anvil cell at room temperature. No phase transition was observed during compression for each sample. A fit of the pressure versus volume data to a second Birch-Murnaghan equation yielded the following parameters for 16 nm, 34 nm and 80 nm, zero-pressure volume, V-0=75.77 angstrom(3), 75.98 angstrom(3) and 76.06 angstrom(3), bulk modulus, B-0=320(7) GPa, 338(6) GPa and 287(3) GPa, respectively. This result along with a reanalysis of previous studies on TiN indicates that the bulk modulus first increases and then decreases with decreasing grain size. The compressibility of TiN has a minimum at similar to 34 nm. (C) 2013 Elsevier Ltd. All rights reserved.