The grain growth rate at the free surface of a WC-Co material was measured at different high temperatures and the microstructure and elemental composition of the material were characterized at various stages of the grain growth process. It was found that free surface grains grew at an abnormally fast rate, and this fast growth rate coincided with the vaporization of the binder phase from the free surface. It is suggested that this abnormal rate of growth is related to a change in the growth mechanism from interfacial reaction limited growth in the bulk of the material to a surface diffusion rate limited growth at the free surface. It is shown that the contact points between grains provide bridges for atomic transport from the high free-energy regions (the small grains) to the low free-energy regions (the large grains); hence, the contiguity of the material strongly influences the rate of growth. It is believed that vaporization of the binder phase allows for an increased atomic mobility at the surface, a reduction in the energy barrier to chemisorption and consequently an accelerated grain growth.