The mixture with 17 wt % Loy Yang (Australian) coal and 83 wt % N-methyl-2-pyrrolidinone (NMP) formed an elastic material at room temperature. Small-amplitude dynamic oscillatory measurements of the mixture by a rheometer showed that the mixture has a rubbery plateau, a characteristic behavior of gel. This viscoelasticity of the mixtures decreased with time (1-5 days), opposite to that for bituminous coal gels. The difference in viscoelastic behaviors between Loy Yang brown coal and Upper Freeport bituminous coal can be attributed to the diffusion rate of NMP into the both coals and the accompanied changes in the "solvated colloid" structure in the coals.