By employing the general expression of temperature Th = |κ|/2π = 1 2πr̃A (1 − ̇̃ rA 2Hr̃A ) associated with the apparent horizon of a FRW universe and assuming a region of FRW universe enclosed by the apparent horizon as a thermal system in equilibrium, we are able to show that the generalized second law of thermodynamics holds in Gauss-Bonnet gravity and in more general Lovelock gravity. PACS num...