Using the differential scanning calorimetry (DSC), the isochronal and isothermal crystallization kinetics of amorphous Fe61Co9-xZr8Mo5WxB17 (x = 0 and 2) ribbons was investigated by the Kissinger equation and by the Kolmogorov-Johnson-Mehl-Avrami and Ranganathan-Heimendahl equations, respectively. The results show that tungsten can improve the activation energy E-1(K) for the first crystallization in the isochronal annealing process and activation energy En for the nucleation in the isothermal annealing process, which can be ascribed to the dissolution of tungsten in the amorphous phase. Meanwhile, tungsten can decrease the activation energy E-2(K) for the second crystallization in the isochronal annealing process and growth activation energy E-g in the isothermal annealing process, which is possibly associated with the formation of W-rich compound after the early nucleation process. (C) 2010 Elsevier B.V. All rights reserved.