Water diffusion coefficients have been measured in myoglobin single crystals and bovine serum albumin (BSA) solutions by the aid of the NMR field-gradient technique. The temperature and the concentration dependences have been determined. The diffusion coefficients in the myoglobin single crystals and in the hydration water of the BSA solutions indicate a strikingly high mobility of the water molecules. Percolation transitions have been observed with respect to the hydration shells and the free water phase as well.