Heterogeneous acid catalysis by heteropoly acids (HPAs) has the potential of great economic rewards and green benefits. Its application, however, has been limited to some extent because of a relatively low thermal stability of HPAs, hence difficulty of catalyst regeneration (decoking). The aim of this paper is to discuss approaches to the problem of catalyst deactivation that could be instrumental to achieve Sustainable performance of solid HPA catalysts. These approaches include: developing new HPA catalysts possessing high thermal stability, modification of HPA catalysts to enhance coke combustion, inhibition of coke formation on HPA catalysts during operation, reactions in supercritical fluids and cascade reactions using Multifunctional HPA catalysis. (c) 2008 Elsevier B.V. All rights reserved.