Amorphous thin films of Ti45.6Ni54.4 and Ti-50.4 Ni-49.6 alloys were deposited onto 3 inch diameter n-type (100)Si wafer by r.f. magnetron sputtering. The activation energy from an amorphous state to crystallization of the Ti45.6Ni54.4 free-standing thin him was found to be 385 kJ mol(-1) by Avrami's method and 374 kJ mol(-1) by Kissinger's method. The values of Avrami exponents are 2.56, 2.65, 2.7, and 3 far isothermal annealing temperatures of 527, 532, 542, and 547 degrees C respectively. The activation energy for the crystallization process of Ti50.4Ni49.6 film-on-substrate is estimated as 287.6 kJ mol(-1) from X-ray diffraction experiment. This value is much smaller than those from Avrami's or Kissinger's methods owing to the effects of the residual compression stress on time thin film and the volume reduction after crystallization.