The present paper investigates the thermal stability analysis of functionally graded material plates subjected to three types of thermal loadings, namely; uniform temperature rise, linear temperature rise and non-linear temperature rise through the thickness, using a novel simple refined theory. The theory, which has strong similarity with classical plate theory in many aspects, accounts for a quadratic variation of the transverse shear strains across the thickness and satisfies the zero traction boundary conditions on the top and bottom surfaces of the plate without using shear correction factors. Material properties are varied continuously in the thickness direction according to a simple power law distribution. A buckling analysis of a functionally graded plate under there types of thermal loads is carried out and results in closed-form solutions thermal stability analysis of functionally graded plates using simple refined plate theory. The influence of various factors such as gradient index, temperature loads, thickness and aspect ratios are carefully studied. The results are verified with the known data in the literature. This theory is seen to behave well, and the results of the sample problem show good agreement with the literature values as seen from the validation checks.