This paper studies the effect of varying substrate temperatures on the resonant charge-transfer process between a scattered particle and a solid surface. Two possible mechanisms for an effect are considered: (1) coupling of the transferring electron to the thermal motion of the target atom on the surface, and (2) changing occupancies of electron orbitals in the solid as temperature varies. Only the latter is found to give a noticeable effect, occurring when the electronic energy level on the projectile is favorably positioned relative to the Fermi level of the target solid. However, even though this effect is noticeable, both mechanisms we consider give very small thermal effects. All other mechanisms, for example those leading to the Kondo (or mixed-valent) effect, are neglected.