The influence of the germanium fraction on the parameters of the solid phase crystallization of amorphous silicon-germanium has been studied. Layers of different compositions were deposited by LPCVD at 450 °C and crystallized at 525, 550, 575 and 600 °C. The crystalline fraction was determined as a function of the annealing time for each germanium fraction and temperature. The incubation and the characteristic crystallization times were obtained by fitting the crystalline fraction to Avrami's model. The values of the diffusion activation energy were obtained for different compositions. The dependence of the nucleation rate and the growth velocity on the germanium fraction and the temperature was studied. The three parameters decrease as the Ge fraction increases; though the stronger dependence corresponds to the nucleation rate. The dependences on the composition and the temperature were analyzed in the frame of a conventional nucleation and growth model and their relationship with the corresponding free energies was discussed.