A new kinetic theory has been proposed in which the formation of structure is assumed to take place in two processes. Combining structural parameters of the model with the viscosity, the variation of shearing stress with time for rheopectic suspensions has been described. A good agreement was obtained between theoretical predictions and experimental results obtained for suspensions of titanate fibers in a polymer solution. Rate constants for both the formation and breaking of network structure were evaluated as functions of rate of shear. The theory was also applied to a suspension of polystyrene particles investigated by Gadala‐Maria and Acrivos to evaluate rate constants. The dependence of the rate constants on rate of shear was found to be different from that for suspensions of titanate fibers.