Grain growth behaviour of fine (∼3μm) and attrition milled nanocrystalline (∼ 32 nm) titanium powers during sintering have been studied. The activation energies of grain growth (Q g) in fine titanium were found to be 192.9 and 142.4 kJ/mol at lower and higher temperature ranges, respectively. The nanocrystalline titanium showed very low values of Q g (54.6 kJ/mol) at lower temperatures and it increased to 273.2 kJ/mol at higher temperatures. The constant (n) in nano Ti system was found to have unusually very high values of 6.5-8.2. The grain boundary rotation along with the diffusional processes could be the grain growth mechanism in nanocrystalline and in fine titanium powders. © Springer Science+Business Media B.V. 2006.