The strength of brown coal-water gels has been assessed by the measurement of the shear elastic modulus of the gels during drying. The strength of the coal-water gel materials has been shown to be related to pH and the exchangeable cation content of the brown coal forming the gel. Manipulation of the coal pH into the alkaline region was found to cause an increase in the shear elastic modulus and rigidity of the coal-water gel, this being due to an increase in the degree of solubility of the coal material. The soluble coal material, humates, are able to form an increased number of entanglements and hence a stronger, more rigid network is built up which exhibits an increased shear elastic modulus.