Most hydraulic-fracture models assume a steady-state power-law rheology model with only an implied temperature dependence and with no shear-rate history dependence. Newer models attempt to model shear-rate history effects, but still do not accommodate the thermal kinetics of crosslinking and breaking chemistry. A kinetic-rheological model was developed that integrates the nonlinear kinetics of crosslinker chemistry with the in-situ changes in fluid rheology.