The reaction of titanium pellet with nitrogen in the temperature range of 1,173-1,473K and under atmospheric pressure was investigated. The diameter of the titanium grains forming the pellet varied between 0.43 x 10(-4)-1.36 x 10(-4)m. The amounts of reactant remaining and products formed in pellet at a particular reaction time were determined by an X-ray diffractometer. The overall reaction was found to be composed of three steps: Ti(s) + 0.15N(2)(g)-->(TiN0.3)-Ti-k1(s) TiN0.3(s) + 0.1N(2)(g)-->(TiN0.5)-Ti-k2(s) TiN0.5(s) + 0.25N(2)(g)-->(TiN)-Ti-k3(s) The second step was very fast and the expressions of rate constants, k(1) and k(3) were determined to be k(1) = 1.5035 x 10(-4) d(Ti)(-0.958) exp( -52,102/RT) s(-1)(m(3)/mole)(0.15) k(3) = 2.427 X 10(-4) d(Ti)(-0.692) exp( - 68,997/RT) s(-1)(m(3)/mole)(0.25).