Thermal transport characteristics of electroosmotic flow of power-law fluids in the presence of pressure gradient through a slit microchannel are studied in this paper. Considering a fully developed flow with a constant wall heat flux as the boundary condition, the governing equations are numerically solved by means of the finite difference method. A complete parametric study is done in order to investigate the effects of different flow parameters on the thermal behaviors of the flow. The results show that the non-Newtonian characteristic of the fluid can influence the thermal behaviors of the flow by affecting the rate of heat convection and viscous dissipation; however, its influence diminishes at higher values of the dimensionless Debye-Hückel parameter. It is also found that the zeta potential, whose value is dependent on the channel wall and the electrolyte solution characteristics, can highly affect the thermal behaviors of the flow, especially at smaller values of the dimensionless Debye-Hückel parameter.