We have investigated the detailed process of agglomeration ofTiSi2thin film on (100) Si substrates as a model system for our recent geometrical model of agglomeration based on the spheroidization at both the surface and film/substrate interface. Agglomeration occurs by a nucleation of holes at grain-boundary vertices as a result of spheroidization at both interfaces and by their subsequent growth along grain boundaries in accordance with the prediction of our model. The critical condition of the ratio of the grain size to film thickness is predicted and confirmed to be between 5 and 6 depending on the magnitude of free-energy barrier. ©1997 American Institute of Physics.