The volumetric changes in the coal matrix (Coal Shrinkage) and permeability properties under various gas environment conditions were studied in the laboratory. The shrinkage and permeability of coal were examined with respect to changing gas type and confining pressures. The shrinkage tests were carried out in high -pressure bombs while the permeability study was conducted in a specially constructed high pressure chamber. Methane (CH4), carbon dioxide(CO2), nitrogen (N2) and a 50% mixture of CO2/CH4 gas were used in the study. The tests showed that under different pressure levels gas type affected permeability and shrinkage characteristics of coal.