Methane drainage and utilization can be a profitable activity for gassy underground coal mines, also it protects our environment by decreasing "greenhouse" gases. One of the key parameters for methane drainage is permeability of coal. The flow of gas and water through coal samples was studied to investigate its permeability to methane and water. A relationship was found between the coal permeability to methane, and its permeability to water. As the measurements of permeability should be in-situ representative, some aspects such as effective stress and gas pressure must take into account. The relationship was verified experimentally for different sets of time. It was found that the permeability of coal to gas and water was different.