The object of this thesis is to investigate a set of constitutive equations which are proposed to describe the behavior of a special class of gelling hygrosteric materials. In recent literature, various relations have been suggested for the analytical description of rigid-viscous type materials which exhibit the thixotropic property of gelling. Various aspects of these relations are incorporated with a general form to which hygrosteric materials have been found to conform. The resulting constitutive equations are then examined for physical reliability by using them to obtain the solution of simple shear flow. The results were found to meet all physically motivated anticipations and it is felt that the proposed equations offer at least a reasonable qualitative description of actual gelling materials.