In this paper propagation of thermoelastic waves in a homogeneous, thermally conducting isotropic plate of finite thickness has been presented in the context of the generalized theory of thermoelasticity without energy dissipation. Dispersion relations of thermoelastic modes of vibration are obtained and discussed. Special cases of the frequency equations are also studied. It obtained in the analysis that horizontally polarized SH wave gets decoupled from the rest of motion and propagates without dispersion or damping, and is not affected by thermal variations on the same plate. Numerical solution of the frequency equations for an aluminum plate is carried out, and the dispersion curves are presented.