<p>This study aims to analyze the flow and thermal behavior of a thin layer of a generalized second-grade liquid with power-law properties over a heated inclined plate, focusing on the effects of gravity and the fluid’s viscoelastic and non-Newtonian characteristics. The purpose of this investigation is to provide a deeper understanding of how these factors influence velocity and temperature distributions and free surface height, which are essential in optimizing industrial processes involving complex fluids. The energy and momentum equations are derived by making use of the long-wavelength approximation, which simplifies the problem by assuming the wavelength of disturbances is much larger than the fluid layer thickness. The solutions of the modified equations are computed with the help of Mathematica software, and along with the boundary conditions, the computed free surface equation is solved numerically by incorporating finite volume technique using the numeric computing platform MATLAB. The results highlight the sensitivity of the fluid’s temperature and velocity distributions to changes in normal stress coefficient and other flow parameters both in dilatant and pseudo-plastic fluids. The thermal field is increased by an increase in the normal stress coefficient and the Eckert number. Moreover, the form and size of the free surface height are significantly influenced by the non-Newtonian fluid characteristics. These findings have implications for applications in areas such as coating flows, polymer processing, and enhanced oil recovery, where precise control over fluid behavior on inclined surfaces is crucial.</p>